The Great Algae-Light Source Experiment

[Floyd R Turbo]

PURPOSE: Design and implement an experiment utilizing the Scientific Method to determine growth rates of algae under various light sources in an Algae Scrubber system on a marine aquarium.

I started this thread based on the discussion in this thread

viewtopic.php?f=2&t=1253 (http://www.algaescrubber.net/forums/viewtopic.php?f=2&t=1253)

And the apparent need to actually design and perform this experiment in order to get an answer to this question. This will likely not be a "once and for all" type of result, but hopefully it will provide enough data to satisfy the majority of our curiosities, and maybe it will point us in the direction of a more refined experiment.

This will be a collaborative effort. All suggestions will be considered.

I will volunteer manufacturing of all acrylic boxes required for said experiment.

At this point, I open this up for all suggestions about the criteria, specifically, the source of light and configuration of the experiment.

It has been suggested on the other thread to start with various mixtures of LEDs, and construct multiple Algae Scrubbers functioning on a single system, such that all devices are driven by the same set of "input" water parameters. So let's start with that...

[Floyd R Turbo]

Ok, back from giving the kid a bath. It was suggested that a system would be designed such that there were multiple small scrubbers all fed from the same system, such as a large tank with a 55g sump and a series of scrubbers all fed from the same overflow and split into multiple branches, with a common return pump. Each individual scrubber would have equal flow and different light configurations. So that is one possible idea.

Another possible idea would be to set up a series of smaller systems and different scrubbers.

However this is done, in order to be a controlled, I would think the most reasonable way to do without introducing too many variables is to eliminate the fish, rock, corals, sand, etc. Just have bare empty tanks and dose given amounts of nutrients equally to each system. This would initially be a low-cost and easily reproducible experiment, and a control group could also be easily used. Although it would hardly be real-world, I see it as the only way of growing algae under perfectly controlled conditions.

Otherwise, using the large single tank idea, you would have to make sure the tank was full of rock that was fully cured, and the system would have to have long-term stability, perhaps 6 months to a year of operation before the 'experiment' could start.

Although you could do a large bare tank and multiple small filters. However I wonder if there would be introduction of competition of species if one scrubber grew more efficient algae and out-competed another scrubber. Results would be skewed.

[sublime]

Awesome :) -- I will be very interested to read the progress of this thread and contribute when I get back next week. I wish I was not headed out right now... oh wait, yeah I do... we will have a lot fun and it will be a much needed vacation.

Thanks for creating the new thread Floyd.

Brandon

[sublime]

Ok, back from giving the kid a bath. It was suggested that a system would be designed such that there were multiple small scrubbers all fed from the same system, such as a large tank with a 55g sump and a series of scrubbers all fed from the same overflow and split into multiple branches, with a common return pump. Each individual scrubber would have equal flow and different light configurations. So that is one possible idea.

Another possible idea would be to set up a series of smaller systems and different scrubbers.

However this is done, in order to be a controlled, I would think the most reasonable way to do without introducing too many variables is to eliminate the fish, rock, corals, sand, etc. Just have bare empty tanks and dose given amounts of nutrients equally to each system. This would initially be a low-cost and easily reproducible experiment, and a control group could also be easily used. Although it would hardly be real-world, I see it as the only way of growing algae under perfectly controlled conditions.

Otherwise, using the large single tank idea, you would have to make sure the tank was full of rock that was fully cured, and the system would have to have long-term stability, perhaps 6 months to a year of operation before the 'experiment' could start.

Although you could do a large bare tank and multiple small filters. However I wonder if there would be introduction of competition of species if one scrubber grew more efficient algae and out-competed another scrubber. Results would be skewed.


I agree... that is why I was thinking of running the lights all on the same screen vertically. Split the same screen up into 3 "sections". Just run optics on the LED's and small black ABS pieces to keep most of the light separated. They way I see it, one would do better, and you might even see the small areas where they mix do the best. You then take the info learned from this "stage 1" and move to stage 2 along the lines of what you are talking about. The idea of the LED's on the same screen is to reduce competition and get a base line to know what to dive deeper into. Taking it to the next level, I think that more diversity in tanks is more important that strictly controlled nutrients doses. (remember I am big into math and stats) I think we should take a statistical approach on this and just create "bio-load weights" that we determine as a group. I was already wanting create a scale for another experiment I am doing for tank bio-load and design. There would need to be a few constants though such as screen size, flow rates and overall light intensity to be effective. However, different nutrient levels and different tank sizes should not matter at a stage 2. Moving to a "stage 3" we could look a very controlled experiment where there are clean closed systems that have various levels of nutrients added over time. I think though, with the first 2 stages we could learn enough to get close to the answer we are searching for to some degree of satisfaction. When I get back, I would be glad to share my VERY simple acrylic design for what I think should be the base line design for this experiment. Then, we can tweak it a bit if someone else can come up with a better design and or idea.

This will be my last post until next week. Keep it up folks!

Brandon

[Floyd R Turbo]

I just wonder if running everything on a common screen as you suggest with sections of different light might actually produce slightly different algae, which would then tend to induce competition, not reduce it. That is why I was thinking of multiple independent systems. So I'm not quite following you I guess. One of our local schools has a marina biology department with over 10,000 gallons of system water (I think it's more like 16,000) and I'm wondering if they would have the capability or the interest in analyzing the algae from each system to determine if there is actually different strains being produced. So the independent systems idea might have other benefits in that regard.

Also MACNA is in town in September. I think that it would be killer if I could coax a few of the 'experts' that will be there into stopping by and looking at an experiment in progress. Talk about an opportunity to spread the word...

[Ace25]

Been brainstorming some more myself.. I think I have a sweet design for an experiment.. in my head anyway. It is very similar to Santa Monica's scrubber. Lets see if I can describe it. Just a simple ABS box, about 18"wide x 4" deep (with bigger bottom plate for stability) x 12" tall. So you have a black box so far on a large base. On my setup I am thinking the base can be as wide at the top rim on my sump so I can just set the ATS right on top on the sump. Next cut holes on the side panels at the top for the pipe that will hold the screens. Make ABS dividers/baffles and cut the same holes at the top for the pipe, put in 4 dividers evenly spaced to give you a little over 3" per section. Now you have a black box with 5 distinct sections that are 3-1/4"x12". Next, drill holes on the outside walls, 2 holes vertical on each chamber, large enough for LEDs to fit into. Glue small pieces of acrylic on inside to water seal the holes, or better yet, piece fit perfect for the inside part of the chamber. Mount 2 LEDs per side on channel aluminum, per section, so 4 LEDs per section for a total of 20 LEDs which means only 2 drivers, one driver for all LEDs on each side. Drill a drain hole at the bottom, install bulkhead, install pump, cut 3" slots on pipe with table saw, prepare screen and cut into 3"x10" strips, and put it together. Anyone understand that or does it only make sense in my head. LOL

What I picture in my head is something similar to coffee bean dispensers you see at the grocery store, tall narrow sections side by side.

[Ace25]

Another idea I just had, make the box deeper, 8-10", and for the holes for the LEDs drill them so optics will fit perfectly through the hole, then a little silicone around the optic to water seal it and all done. As long as you make sure all the LEDs are spaced correctly on the C channel you should be able to easily remove the LEDs and make changes as the experiment moves forward (thinking velcro to secure them to the box, bottom will be resting on the base so no weight pulling on it). It is only 2 LEDs on a good size piece of metal and run at 700mA, so no fans should be required.

[Floyd R Turbo]

That sounds interesting, I hadn't really considered the idea of making the 'black box' and then drilling holes for the LEDs. I would likely build mine to mimic Rygh's builds, which involve using a diffuser to blend and even out the light. Just poking LEDs through holes and having them 1-2" from the screen is not going to work, IMO. Putting lenses on them will make it worse. I believe that we need to have as even coverage as possible.

In fact, on that note, I think that one of the 'control group' systems, besides a non-scrubber system, should be T5HO and another CFL. This will give us opportunity to also perform a benchmark comparison test between the different sources of light.

All this being said, I am not against someone else running an experiment that they deem to be valid. Right now I'm thinking that I have a basement storage room that needs to be cleaned out anyways, and I could easily build a rack of tanks and run a couple of circuits down there...the mad scientist in me is waking up...

[Rumpy Pumpy]

Excellent!

I'll look forward to seeing this unfold

[Floyd R Turbo]

What would one use as an additive to create a 'soup' of nutrients to feed the screens in a bare-tank system?

At a minimum, I would be needing a source of N and P. Dry ferts used for planted FW tanks would seem to be appropriate, but if I'm trying to duplicate what is created in nature, is there something more complex?

Still thinking of other parameters for / thoughts about the multiple independent bare tank experiment.

1) If I want a control group using T5HO, then I would be restricting all screens to 20" wide and 3" tall, minimum, for consistency. If I'm running on 10 or 20 gallon tanks, this is way overkill filtration and flow. Maybe should ditch the T5HO control group idea.

2) I will need to account for cycling of the system, or pre-cycle the tanks. Perhaps using a small amount of live sand or commonly cured base rock rubble. Again, throwing a potential variable in there, but I do have a 25g container full of small pieces of dry rock that I could cook up in a common container.

3) Each system will need to be on the same display tank lighting cycle and scrubber lighting cycle. Simple enough to do with some SunBlaze T5HO strips with tanks ganged together over the display tank section.

4) A dosing pump system would be used to provide consistent nutrient loading of each system. Probably one pump with some kind of manifold to split the dosing across all systems, so that differences in individual doser units is eliminated.

5) The system would be saltwater based (figured that was worth mentioning)

6) Each system would be identical in all ways except the source of light: same materials, piping, overflow, contents, same brand and model of feed/return pump. Each pump would be tested for flow rate verification.

Scrubbers will likely be located above the tank for ease of design (no sumps). But undecided about making them in enclosed boxes. But I just had a bright idea. Since I'm setting up my acrylics fabrication shop, I might as well make my own system. I could make a one or two long tanks and put in dividers, add bulkheads, then make a second set of tanks below that would house the ATS units. These could have one common display tank light system and everything else would be isolated, as long as the welds were all bubble and leak free. This way I could make the ATS units rigged for enclosed 3D growth to maximize results.

Hmmm...

[Rumpy Pumpy]

What would one use as an additive to create a 'soup' of nutrients to feed the screens in a bare-tank system?


You could just bung in some live rock and dose ammonia or stick something in there to rot, some dead prawns or whatever.


I wonder though how much the running the experiment on a "bare tank" would be relevant to the real world of reef keeping?

[Floyd R Turbo]

I don't care much about relevance to a real-world scenario. I care about creating a controlled scientific experiment without extraneous uncontrollable variables by which data can be extrapolated that shows algae growth at given wavelengths of light. I feel the only way to do this is to remove all unknown variables from the equation and focus on growing algae.

[SantaMonica]

To grow the most, have a live animal that is producing urea.

[Floyd R Turbo]

Well, couldn't I just dose urea?

My goal is to create the environment that would be produced with live animals, however without actually using them. I know that this information is probably readily available, but at the present time I have very little spare time to devote to digging up this information. So if anyone has it or can point me to it, that would be much appreciated.

A couple of reasons why I don't want to have a live animal is because there are too many variables that can result from that, plus I want to be able to put a definitively measurable and predetermined bio-load on the system.

There could be several benefits of analyzing the results of an experiment performed in this manner, such as finally getting answers to exactly how much N and P and other nutrients a scrubber is able to absorb, and then sending water samples to laboratories to get analyzed and find out what the 'scrubbed' water is composed of, before and after. Perhaps some of these results can then be thrown in the face of the anti-scrubber crowd as at least somewhat scientific evidence of what modern scrubbers are actually capable of, albeit that there will I'm sure be detractors saying that it is far from a real-world environment.

But, the next step after the experiment is complete would be to then add fish, corals, rock, sand, feeding and monitor...

[SantaMonica]

The trouble with mail-in water testing is that the water composition changes hourly, and after 24 hours it's really not the same water. Microbes and bacteria continue their consumption of DOC the whole time. The changes are so great that when biologists take ocean or lake samples for testing, they either do the tests immediately on the boat, or they count the minutes from the time of sampling to the time of testing.

[maglofster]

Could Guillard F/2 Formula be something to be used as fertilizer?

For measuring phosphate, a guy on our Swedish reef forum (he's a chemist) has presented a modified protocol for Hanna Checker Phosphate (HI713). This method gives consistent and pretty reliable results.

[Floyd R Turbo]

Yeah I wondered about that SM. So I guess the way to do it right would be to perform the experiment with lab equipment handy. So maybe keeping it simple for the initial run would be fine, just harvesting and weighing and such. Still, I'm 30 minutes from Iowa State University, which would probably have some appropriate equipment...the local marine biology department I mentioned basically told me they couldn't do it.

[SantaMonica]

The best measurement is probably dry weight harvested. Really dry, like 3 hours in an oven.

[salty joe]

Hey Floyd, thanks for the link. I think it is great that you are doing and documenting this work.

How about this? For the "display tank" use a couple rocks with algae etc. on them and go barebottom. You could use just one spotlight for the rock. For nutrients, you could put a grocery store clam in the display and switch it for a fresh one as needed.

For starts, what do you think of running the 3000K T5 versus the 6500K T5? We all know the 3000 works well, but the 6500 is designed for vegetative growth and I don't know that the 6500 has been tried. Who knows, they may work equally well but grow different algae. The gist of an article I read awhile ago was the filtration ability of different types of algae working on the same body of water is greater than the sum of the individual algaes. Anyway, T5 is something that you are familar with so thought it might be an easy start.

[Floyd R Turbo]

That was the control group idea, use 3000K T5HO for comparison. The problem is that 24" T5HO means 20" screen and that's pretty big even for 1 lamp per side (20 x 3 minimum really). But then again if I make a total system water of 30G it's only double-sized. But it also increases pump size. I guess I wouldn't have to use the full length of the lamp. I don't want to run into a need for a bunch of larger pumps to drive screens. I'd rather limit it to smaller pumps.

Again, the idea of adding any rock, sand or dead matter throws in an unknown and non-controllable variable. So I am still looking for a chemical mix that can be dosed into the tank on a measured basis that will closely simulate by-products of animal waste and uneaten food.

[Ace25]

I am a little confused on why you're so interested in making such a control scenario for the tank. Since none of us have the lab facilities really required to do this properly (daily lab testing of water) we just have to do the best we can with what we have. I would think as long as you are running multiple test scrubbers off the same tank, that will give you the exact same data as a control tank, ie, which lighting gives the best growth of algae. It shouldn't matter what the tank is like (sterile/ferts or full on reef) because every screen will get the same water. Even if the water isn't the most ideal in nutrients for the algae, it will still show us which lighting gives the best growth regardless of tank conditions.

Then again, maybe I am misunderstanding the goal here.

[Floyd R Turbo]

It's a valid question and I see where you are coming from. I guess what I am trying to get at is that let's say there is a slightly different type of algae or mix of algae that grows under LED WW only, Deep red/blue/ww mix, blue only, etc. Then let's also say that one screen is particularly efficient at growing algae. That screen will in effect out-compete the other screens, and then the results will be skewed. Granted that the end effect will show which combination of lights is the most effective, but what I am trying to measure is nutrient uptake accomplished by each screen driven by a given light source. That is truly useful data. Otherwise someone could step in and say the experiment was fundamentally flawed and while most of us could not care less what the hard-core detractors think, I don't want to give them any ammo either.

The other reason for splitting up the systems is to finally get some answers to the efficiency of nutrient uptake by algae in a scrubber configuration. By controlling dosage I can maximize growth results. Maybe this will shed some light on exactly how powerful scrubbers really are. Once that initial data is in the books, is would be very interesting to expand the experiment to include other forms of filtration for comparison and see how they stand up. I would call that experiment "Take the Scrubber Challenge" in honor of Pepsi. Which is way better than Coke according to the test results. But Coke has good marketing. See a similarity?

I can deal OK with using non-lab grade testing equipment, as long as it's a good quality kit like Salifert for Nitrate and a good meter for P, like Milwaukee or Hanna (the $200 one).

[Ace25]

LOL, I see, the RC people got under your skin too.. I was banned long ago from RC (2005) for trying to prove that actinic lights were far more important to corals than what most people thought. I tried to prove the wavelength and photosynthetic properties of actinic lighting and the mods banned me because they said actinics were only for visual use, to make us think the water looked more like the ocean, but had no real value to the tank. I challenged the almighty mods and gave scientific data and was banned for it. From that point on RC has been more of a joke to me than anything.

I see where your going with the experiment at hand... but to me, that seems like a different experiment. First experiment, test out various types of lighting and hopefully find a way to identify algae strains. Once we get the best type of lighting for maximum growth and which strain grows the fastest, we can move on to experiment 2, to see how much nutrient uptake the top 3 lighting and strain combinations can do, which is what you are talking about. Take the top 3 winners in experiment one and move them to experiment 2 to see if they correlate, ie. winner of Experiment 1 for most growth is also the one that does the most nutrient uptake. We may be surprised and find out the second fastest algae grower is the fastest at nutrient uptake.

[SantaMonica]

A note about multiple scrubbers on one tank: As one screen starts to grow, it will limit the growth of the other screen(s), making you think the other screens are less effective. This is easily observed in my testing of the 25: When one side is full, the other side does not grow, even if left for two weeks. Then when the full side is cleaned, the non-growing side grows and fills up in 3 days. And this is under the control of one cube per day.

Is similar to two water bottles connected by a tube at the bottom: If you add, subtract, heat or cool the water in one bottle, it will affect the other bottle.

[Ace25]

I would think the same decline in growth would happen along all the screens. At least how I picture it in my head. Say 5 independent boxes, each with a 3"x10" screen and its own pump, something like a maxijet 1200. If each small screen has its own pump, and you line all the pumps up together in the sump to intake water at the same point, I would think it could work. You would have to start them all and clean them at the exact same time. Each screen isn't big enough by itself to scrub enough, and on the LED experiment use only 2 LEDs per side in order to get growth spots since you want to see how much an LED will cover on its own. With LEDs you can mix a red and a blue and be able to see if algae grows better on the blue, red, or when mixed in the middle.

To take it a step further, you could test each setup for 30 days, then once you have the data swap the screens around in different lighting to see if the algae still grows or declines.

[SantaMonica]

No, as soon as one starts growing more, it's filtering will increase exponentially by increased water contact and growth area. It will then consume all nutrients and not allow the other screens to grow.

It's the parellel resistors situation.

[Floyd R Turbo]

That's exactly what I was getting at, thanks SM for confirming. The exponential growth factor is something I had not though of either, but it fits in with logic.

For instance, my current jury-rigged top-of-tank scrubber was at just enough growth to have about 1" of 3D at the bottom late Friday (day 4) and the 2nd (high) drain was dry. Now it's easily 3 or 4" in the middle (day 6) and the second drain is flowing fairly well.

[salty joe]

If 2 screens at once is a problem, how about running 2 screens on alternating 12 hr photoperiods? You could use an unlit sump and dose accordingly to mantain a consistant nutrient load. Maybe use nutrient loaded topoff water in an ATO. Wouldn't plain old amonia provide useful and easily measurable N? There has to be a similar chemical you could use to provide P. I'd bet Randy at RC would answer that one for you.

[Floyd R Turbo]

Today I had a conversation with a guy who has been in the hydroponics industry for 15 years. He had some very interesting things to say about light spectrum and intensity. I believe I finally have a good answer for the 3000K vs 6000K and up issue.

When I brought up T5HO and people experiencing better growth with the 2700-3500K spectrum, it threw up a flag for him. The issue, apparently is not that the spectrum is better, it is that the lower Kelvin rating is more intense. I can't recall all the details of the conversation (we spoke about many things) but this is basically what the K rating issue boils down to. The light given off in the red spectrums is more photosynthetically active than that in the blue spectrums.

I know this is going to raise some additional questions, mainly how do you also hit the blue peaks and with what amounts, but that may not matter. It has to do with vegetative growth vs flowering growth. I'm going to talk to him again and try to get this straightened out in my head.

We came about that point when discussing LED lighting for algae / hydroponic growth. A lot of the better results seen so far with LED lighting have been seen using lots of red (630nm) LEDs, and some good growth with 5W deep red (660nm) LEDs. That brought about a discussion regarding those. As it turns out, if you take arrays of the same wattage of 660nm Deep Red LEDs and 630nm LEDs, the 630nm Red LEDs will strongly outperform the 660nms, because they flat out are just that more intense. The reds are also more intense than the blues. This is why better growth is achieved with lights shifted toward the red spectrum.

This may not be the greatest explanation, but I'm working on it. For me, all the information I got out of the conversation pretty much put the nail in the coffin of the spectrum debate.

More to come.

[Floyd R Turbo]

One more thing to add. He did mention that to his knowledge, no experiments have been done (except for one by NASA, which I will now start to look for - SM, got that one?) to determine algal biomass growth rates under various spectrums.

[SantaMonica]

Haven't seen it. Not really been looking into spectrum much.

[salty joe]

The issue, apparently is not that the spectrum is better, it is that the lower Kelvin rating is more intense. I can't recall all the details of the conversation (we spoke about many things) but this is basically what the K rating issue boils down to. The light given off in the red spectrums is more photosynthetically active than that in the blue spectrums.

More to come.

Well, rate of growth/watt is where it's at. Are you saying that lower K is more efficiently produced, meaning less electricity is used? IDK, could be. It could also be the case with some type of artificial light, but not with other types. Can't wait to see what you come up with.

I heard through the grapevine that researchers at Cornell are working with algae.

[Floyd R Turbo]

That's the other place he mentioned, Cornell and NASA.

But yes, if you wanted to look at it from a growth rate/watt viewpoint, that was exactly what he was saying. 630nm Red outperforms Blue and Deep Red. It is why you get better growth from 2700-3500K than 5000-6000K.

[rygh]

Some interesting statements. Good data!
The problem is, while he may have 15 years growing things, that can mean a lot, or nothing, when it comes to knowing spectral response.
Like so many aquarium experts you run into.

I do agree that red LEDs are more efficient. And in terms of photons / watt, likely better.
The red (GaAlAsP I believe) are the very efficient. The whites are blue LEDs with phosphors, so not only
is the LED less efficient, it then gets converted from blue to white.

Now as to red being more active than blue, hard to say.
Theoretically, a blue photon has more energy than a red....

----

My real opinion after a lot of these debates - It does not matter all that much.
There are so many variable, it is impossible to optimize the last bit of wavelength.
So put some red, some blue, some warm white, and a few extra of whatever you want, and call it a day.
The flow and screen size seem to play a much larger role.

[Floyd R Turbo]

I think there is some real truth to that statement about flow and screen size. However I differ with you regarding the last bit of wavelength, otherwise I don't think I'd be up for doing this experiment. With T5HO or CFL, the anecdotal evidence has shown that algae grows better in lower K ratings. I don't think there's much out there for growth rates with mixed lamp setups, people usually choose one or the other.

We can definitely take a page from the hydroponic grower's book and use that as a starting point. The LED grow lights for plants currently are very spectrum focused, the goal being not to waste any energy on spectrums that are not needed. I think this eventually should be the goal of the LED scrubber - completely, totally awesome growth with minimal energy.

So here's what I'm thinking. The simplest setup would be one LED on each side of a screen. But using 3W LEDs and driving them below their maximum, you are looking at maybe 2W each or a 4W scrubber. Counting the power as double T5HO/CFL, then that's 8W. 2 LEDs/side would be 16W equivalent, and you would see the effect of crossover between the LEDs. I don't know if this is what I want to actually see, or not. Adding crossover between LEDs might add in a factor of over-intensity (photo-inhibition or chlorophyll bleaching) that I wish to avoid. But I suppose a diamond diffuser plate would take care of this. I may have a source of a decent PAR meter to use for testing fixtures. So this may take some build testing.

Well, more to think about. Enough for tonight.. Getting tired, long weekend and next week ahead...

[rygh]

I guess I should not have stated it in such general terms.

You can definitely get the wrong kind of light. Both with LED and CFL.
But getting a decent amount of red is pretty easy, and I feel that once
you do that, it is no longer that critical.

BTW: I did try one of my royal blue / cool white LED clusters.
I built those for the main tank, and tried them a couple of weeks on the scrubber.
The results were lousy, even though the overall output was quite a bit higher.
Specifically - I replaced 2 red + 1 blue with 2 more modern cool white + 2 royal blue.
I think I had some pics toward the end of my old LED thread.

I wish I had more time for real experimenting. Sounds like fun.

[Floyd R Turbo]

When you say the overall output was quite a bit higher, are you talking about the output of the light? Meaning that you threw more light at it (more watts?) and got less growth? I'll have to look at some of your threads again...

[Ace25]

I agree with rygh about the LEDs. The blue LEDs put out about 2x as much PAR as the red and warm/neutral white LEDs. Only the cool white LEDs equal the par output of the royal blues. So what I think he was saying is that with cool whites + royal blues you get 2x as much PAR output as going reds/warm whites but you get much less growth, so spectrum is very important. In the 2 weeks I have been doing my little experiment my results seem to be the same as rygh, the side with the royal blues is giving less growth than the side with warm whites even though it is much higher in PAR on the side with the royal blues.

[Floyd R Turbo]

This is one of the things that Sean at Light House made a comment about. He was very pointed when he said that what he felt that most people were completely missing was the concept of chlorophyll bleaching when light intensity was too high. So it is very possible that there is more than one factor contributing to lower growth when using CW/RB when compared to R/WW.

If I remember right, you needed more power in the blue band to get the photosynthesis to match what you get from the red band, to the point of overpowering the algae. I have to talk to Sean again to see if I understand this correctly. I also might ask him about the difference between photo-inhibition and chlorophyll bleaching.

[new2scrub]

are you using cree led's? I made my main display light from them and it works flawlessly .I would love to not have to change the 4 curly-q's on my scrubber every 3 months like I am doing now.

[Floyd R Turbo]

I'm not using any LED right now, but I prefer them.
One correction, lumen per lumen blues and reds are on the same level as far an photosynthetically active radiation. That was my misunderstanding. So what it comes down to is still what grows best under what light, so in essence, the experiment still needs to be done because there really is no answer to this question that comes from data generated by anyone doing something similar for algae, specifically.

[kotlec]

Waching with interest. Please bring some news . Cant wait. ;)

[Floyd R Turbo]

I have figured a short-cut to building a bunch of acrylic systems. Petco $1/gallon tank sale. Going to clean them out of a bunch of tanks.

[Floyd R Turbo]

Unfortunately I won't get a chance to go to Petco until next week. I hope they have a bunch of tanks left....

[kotlec]

Did they had ? :D

[sublime]

I have been too busy to get involved with this just yet. However, I like where things are going and I look forward to seeing some results and very soon, providing my own.

Brandon

[Floyd R Turbo]

They're out of 20Hs and 40Bs but I'm not going to worry too much about it. If I can manage to get a bunch of 20Hs that would work, but 40Bs would be too big, and I might still just make them myself.

[Floyd R Turbo]

The experiment is officially back on. SeaTurtle's thread viewtopic.php?f=2&t=1483 (http://www.algaescrubber.net/forums/viewtopic.php?f=2&t=1483) shows a pretty good example of how powerful algae can be.

So, I'm going to replicate his idea and use it to test a couple of different scrubbers.

PHASE 1 will entail 2 separate systems, each running a single-sided scrubber. Each system will have the same size scrubber screen and feed pump, and will be lit by a custom-made LED fixture. I had these custom made after months of discussion with someone with over 15 years of experience in the horticulture industry. This test should, at a minimum, confirm if algae responds to the same grow-light spectrums as plants, or if there is indeed a difference whic requires additional research.

System 1 will have an LED fixture containing 112 LEDs, 98 660nm "Deep" Red and 14 425/435nm Blue. This fixture is custom 'tuned' to the Chlorophyll "A" spectrum.

System 2 will have an LED fixture containing 112 LEDs, 98 630nm Red and 14 460nm Blues. This fixture is custom 'tuned' to the Chlorophyll "B" spectrum.

The system water will be RO/DI water with Instant Ocean Sea Salt, mixed to a salinity of 29ppt. A measured amount of fertilizer (brand TBD) will be mixed together with water from the system until fully dissolved, and then added to the system. These will be the initial conditions of the system.

One variable that will not be completely controllable is temperature. I'm 100% positive that my wife will not let me do this in the basement. Therefore, the garage it shall be, and who knows what the temp will be come mid September. But I will probably use a couple of cheap heaters to maintain a minimum temperature, at least. And, the temperature of each system should be the same since they are sharing the same space.

The water will be tested initially to establish a baseline, prior to addition of fertilizer.

A few hours after the fertilizer is added, the water will be tested again.

The scrubber will be started "from scratch", meaning the screen will have never seen water until the fertilizer is mixed in and the feed pump turned on.

There will be no lighting over the tank.

The scrubber lights will initially run on a repeating cycle, yet to be determined. I'm thinking 4 on, 4 off, continuous cycle.

Water in both systems will be tested on a daily basis as the same time of the day, using the same newly purchased API liquid regent test kits for Ammonia, Nitrite, Nitrate, Phosphate, and pH. I'm not dipping my Hanna pH meter in this junk, no way.

Growth on both screens will be photographed each day and harvested on the same day (TBD)

Algae will be strained to remove as much water as possible, then weighed.

If I can get away with it without the wife knowing, algae will be spread out on a baking sheet and dried in an oven under low heat for 30 minutes or so, then weighed.

As testable levels of Ammonia, Nitrite, Nitrate, and Phosphate drop, additional fertilizer may be added to facilitate algae growth

This experiment will continue for a time frame yet to be determined, basically until I start to see a significant pattern.

What I expect is that both systems will grow copious amounts of algae.

What is not known is whether one system will grow the algae faster and thicker than the other, and whether one will pull nutrients out of the water faster that the other.

This isn't complete, but that's the general idea.

PHASE 2 will entail starting up a single system from scratch, with all parameters the same as PHASE 1, with the exception of lighting.

The lighting will consist of using both the "A" and "B" fixtures together, both illuminating the same side of a screen. The fixtures will be moved slightly further away from the screen, then angled towards each other so that the light from each fixture overlaps on to the same area. This in essence will create a single 4-band fixture.

The parameter that will be assessed in PHASE 2 is whether combining the "A" and "B" band fixtures will have any kind of significant additive effect.

Since I only have the 2 fixtures, I find myself either limited to running a single-sided scrubber, or running a system using a couple of mirrors at a 45 degree angle to the screen and placing the fixture at a 90 degree angle to the screen. The latter sounds too complicated to build.

There may be a Phase 3 where a fixture is placed on each side of the screen to see if there is any difference, but that would be skewed due to running a double-sided screen being 2x as powerful, so I'm not sure that would yield useable data. Plus, I have a tank that can use the fixtures.

Hopefully, this will "shed light" on the algae spectrum issue. It may not put it to rest once and for all, but it will probably provide enough data to create the next generation of LED scrubbers. But, like any good experiment, it will likely raise more questions than it will provide answers.

[srusso]

Nice write up! You seemingly have eliminated any errors on this one! I totally get the experiment now. I missed a lot of those details when we last spoke! You can't blame me though I was on my scooter! LoL

Good luck, although you may find the true answer to which type of LEDs to use... Your experiment wont be as cool as his dog poop scrubber experiment! Hahaha Just kidding!

[rygh]

Sounds like a great experiment !!!

I keep toying with the idea of more LED experimentation, but my regular to-do list is so long that it is hopeless.
In my idea, I was going to go smaller scale.
Basically, make single led clusters, each enclosed with a 3" PVC pipe, that also acts as a reflector.
Clusters would be variations on the 2 reds, 2 blues, warm whites.
I would end up with a bunch of 3" circles of growth. And mostly just look at them to see what is best.

[Floyd R Turbo]

Ok, I've got the fixtures finalized now and they're mounting the chips. As it turns out, they had a few standard PCBs for dual-switching, so I was able to have them make each fixture a different combination of LED on each switch leg, so effectively I now have 4 fixtures.

Fixture #1 has 49 630nm Reds and 7 460nm Blues on switch leg #1, and 49 660nm Deep Reds and 7 425nm Blues on switch leg #2
Fixture #2 has 49 630nm Reds and 7 425nm Blues on switch leg #1, and 49 660nm Deep Reds and 7 460nm Blues on switch leg #2

This was the manufacturer's idea, and I'm glad he came up with it. What I can do is now test the following combinations:

630/460
630/425
660/460
660/425
630/425/460
660/425/460
630/660/425
630/660/460
630/660/425/460

Some of those combinations will require using both fixtures on the same side of the screen, which will have to be taken into account with using a PAR meter and messing with the distance from the screen and maybe some screening material between the fixture and screen to diffuse/reduce the light.

So it's not perfect, but it also not costing me an arm and a leg, and when I get done, I have 2 4-band fixtures that will probably kick ass.

[sublime]

Awesome man. It will be interesting to see what you find out. Also, yeah, those will be some nice fixtures to have regardless.

[Ace25]

Wow! That is awesome! You are certainly going to be able to put all the pieces together in regards to LEDs and Spectrum with that light. That is a better light than I could have imagined myself so great job on the design. I am anxiously looking forward to reading your results. I think your results are going to lead to many more people to add an ATS to their tank because with your results your going to be able to make it smaller. I am thinking with the right LED combination you can cut a SM100 in 1/2 and get the same results.

[Aeros]

Any updates? I am holding off LEDs till the outcome of this test is compete.

[Floyd R Turbo]

I just got the fixtures this morning. Unboxed one and lit it up, sure is bright. I was seeing little spots everywhere for a while...

[iggy]

Here is a brief summary of Kessil on tailoring LED packaged lamps to grows terrestial plants. It is interesting ideal if it save watts.


Different spectra have different effects upon plant growth. With combinations of Dense Matrix LED units, the grower can customize the light environment of their grow room just as engineers customize the spectral output of individual units with different diode configurations. Optimize your spectrum.

[Floyd R Turbo]

Checked out the fixtures a little closer today...they're both the same. The company didn't make them as I specified. I also have an extreme headache from looking at these while taking pictures. They're beyond bright man!!! So I don't know what I'm going to do, I can at least test A and B and combined bands, just can't test the crossover mixtures.

[jnad]

Hello!

You should be very carefull to look into led lights.
I am very sceptical to the use of leds, it is ok to use led in a scrubber i think, but i am very doubtfull to use led as main light for the aquarium.
Read this:
http://www.afssa.fr/Documents/PRES2010CPA14EN.pdf

jnad

[kotlec]

As per this study , too bright glare from LEDs can damage eyes, especially blue spectrum when staring directly at LED beam. First of all I doubt my corals having eyes at all . Second - I already told my fishes not to look directly to LEDs. So they are warned :mrgreen:

Seriously I thing everything in this life is dangerous, especially if misused or used not at right amounts.

[Floyd R Turbo]

That's interesting. I forwarded that to a lighting expert (in the country) to get his take on that.

We're a little off-topic here, but one thing I noticed that was absent from that report was the recent verification of scotopic sensors in the eyes. In case you don't know what I'm talking about, there is one guy (can't remember his name) who has been saying for 25 years that there is another retinal component that is specifically sensitive to the perception of blue light. This has recently been verified. So there are rods, cones, and this third one. What it means as far as the general lighting industry is that higher kelvin lights are perceived as brighter by the human eye, thus lumens can be reduced. America is about the only country in the world that has been stuck on 3500K lighting, every other country in the world, in particular those close to the equator, use mostly 6500K. So higher blue content lighting has been in use for decades and to try and pin some kind of harmful effect on blue or bluer lighting to me is shaky at best. Some are arguing that using higher K light in night shifts messes with circadian rhythms and some have gone so far as to argue that it can cause breast cancer. They do this by overlaying a satellite shot of the earth at night with the instance of breast cancer. Again, picking one thing as the cause is shaky at best - there are thousands of other factors that can contribute to cancer, diet and proper intake of parent essential oils being the top two, both of which are severely lacking in those areas lit up in the night sky due to over processing of food and busy lifestyles.

End of rant.

Back on topic, yeah never stare directly into LEDs because ouch. Dots everywhere. Headache.

I know this is what lots of people are waiting for

http://i611.photobucket.com/albums/tt191/FloydRTurbo/LED%20ATS%20Experiment/DSC03004-fixture2cct12.jpg

Just for reference, this picture was not taken in the dark. It was taken with all room lights on. This thing throws so much frickin light it's not even funny. I had both of them on and the entire kitchen looked like an alien spacecraft cockpit or something. My wife said "what the f$#% is that???"

[sublime]

Those things look awesome!

I want to put two of those on my Christmas list! Where did you get them again? (Of course after you tell us how awesome they work!)

Brandon

[jaczal]

Floyd, I read in the development of biotechnology on chlorophyll a and b. It shows that:
- Chlorophyll a - a basic, blue-green pigment, present in all fotoautotrofów except bacteria;
- Chlorophyll b - green-yellow pigment found in higher plants and algae, chlorophyll AIW whatever lesser amount.
It follows that the optimal system LED 430nm and 660nm will. The only question which the spectrum of light to give more.
In terrestrial plants Chlorophyll absorbs mostly blue spectrum, and the water red. However, in case the filter may find it confusing.
So I'm looking forward to the results of your research.

[Floyd R Turbo]

What you may have been looking at is the growth versus flowering issue as well. If you search around enough, you will find there are fixtures more geared towards growth which are heavier in red, and fixtures geared toward flowering which are more broad spectrum, including much heavier blue as well as white and UV components. The evidence is extremely good that 455/460nm Royal Blue is the key spectrum for coral growth, and pretty much anything else is aesthetic to a great extent, and promotes growth to a much lesser extent in an of themselves. There is an additive effect for additional color spectrums but they is not necessarily primary for coral growth. This is of course an over-generalization, but that's the gist of it.

As far as algae growth, the reason I'm doing this experiment is specifically because there is little to no data for our specific set of circumstances. So I am interested as well in the outcome.

[Fish Friend]

Hi, I am new to Marine fish keeping but I have had high Nitrate problems although all other parameters are fine. So I found your site by accident and I have constructed a scrubber following your design.In the Uk we have a number of sites offering Growlights so I bought a 125 watt grow light & reflector unit and placed it in front of the screen in my sump. Hey presto! 3 weeks later and my nitrates are dropping fast.
However after reading your instructions more carefully I may have the wrong light spectrum.
On the lighting website it said to use the Blue spectrum 6400k for growing & propagation and the Red spectrum for flowering.
So after reading through your article again I bought a Red spectrum bulb but I haven't yet noticed any change in the algae growth.
With the 6400k bulb the algae growth was very dark brown, I will keep you posted on the growth with the Red 2700k bulb.
Here is a link, hopefully, to the growlight website, I haven't seen any similar being used by anyone on your forum but they may be a useful addition as they are quite long.
http://www.enviro-gro-lites.co.uk/products.asp
Regards
David

[Reefaholic]

Hey Floyd

Any word yet on results of new equipment

[Floyd R Turbo]

Nope. I have no idea when I will get a chance to start this experiment. There has been a new development at my work that is likely to take up a lot of my time.

[Floyd R Turbo]

Looks like I will be working on designing my setup finally over the next month or so. I have also procured a couple of e-shine fixtures to add to the experiment. Actually I might just use those on one of the tanks I maintain. If you want to call it that. I have 2 clients that don't see the value in cleaning a tank when the fish look fine. One has Nitrates at 500ppm, the other between 600 and 800ppm. Tough economic times suck for fish in tanks at restaurants that are just squeaking by. So these tanks are going to fall under the 'experiment' as well. One of them will likely get converted to a full blown reef, if I can talk the owner into it (he's a former reefer)

[Floyd R Turbo]

After several epic failures to convert an excel file to a html table format, I just uploaded this to google docs

https://docs.google.com/spreadsheet/...WZrS3Z6endKTXc

This is a comparison spreadsheet of PAR readings below an e-Shine 50W fixture and a Nova Extreme 1127 T5HO fixture with 2 x 24W 3000K grow lamps (the ones I use).

A few considerations to make:

The e-shine readings were taken with the fixture out of the box and turned on a sum total of less than 5 minutes prior to the test. So there might be some variation in long-term readings.

1) I ran out of new T5HO lamps so I had to use ones I had removed from the scrubber already. So the T5HO lamps are at the end of their useful scrubbing life, 90 days x 18 hours = 1620 hours. I'm not sure how this affects the PAR readings. The Nova Extreme 1127 fixture was brand new out of the box, I just switched the lamps.

2) All readings were taken with an Apogee meter with the fixture approximately 2" from the top of the sensor. The sensor was pointed straight up. I made a stand-off bracket our of Duplo Legos (highly scientific) and laid white graph paper on the table below the fixture and marked each measurement point on 1" increments. I measured along the center axis of the fixture, then along lines 1" and 2" from the center axis.

3) I did the e-Shine fixture first, then the Nova. The Nova fixture has an extra row of data points at the ends nearest the endpoints of the lamps. I didn't realize this until afterwards. Removing these data points (A ans S) raises the sum and lowers the average so that the E-Shine is about 140% of the Nova on both overall.

4) I had to let the Nova fixture warm up for a while before the readings were consistent along the axis. I took one set of readings along half of the center axis, then did 1" and 2" off that half, then went back to the center axis on the other side and the readings did not mirror the first half. When I went back to double-check the first half center axis, the PAR values had dropped 10-15%. I let the fixture run for about 20 minutes, then the readings had stabilized. Perhaps someone can shed some light on what is going on there. I thought T5HO was supposed to get more efficient as they heated up.

As you can see from the results, the e-Shine fixture, even though it has a smaller profile (both the enclosure and with respect to the element exposure, meaning the T5HO are longer and the window area on the fixture is wider), it is higher on every number except for the extreme corner data points.

On the flip side, the max to min ratio on the e-Shine fixture is much higher. Meaning that the readings in the center of almost 700 PAR and 120ish on the edges is a larger swing than the Nova of 460 to 110ish

The PAR meter reads out a little higher under the blue LEDs. Being this close to the fixture, there is little blending effect so the e-Shine fixture has a much higher variance of intensity throughout the sample field. The Nova fixture has a much more consistent peak intensity in the middle of the fixture and the number generally drop off as you get away from the dead center of the fixture.

I messed around with the PAR meter a bit to test a few things. Obviously pointing the sensor straight up all the time did not result in the maximum reading. On the +/-2 lines, if I pointed the meter towards the source, the number would increase, significantly at times. At the center line, I was able to get maximum PAR readings of over 800 on the e-Shine fixture. I was able to get readings of about 500 on the Nova fixture, but barely. +/-2 readings on the Nova fixture would also increase, but not as noticeably as the e-Shine fixture.

So being my first run at doing this, the results are far from scientific, but nonetheless very interesting.

What it tells me is that at the worst case, the e-Shine LED fixture is comparable if not better than the Nova T5HO fixture. Even if you de-rate the e-Shine fixture by, say, 20% for end-of-life after 7 years of running at 18 hours/day, then compensate the Nova fixture to take into effect the lamp intensity drop-off from 1600 hours of use over 3 months (increase output by 20%) then they are equal with the Nova at it's best and the e-Shine at it's worst.

Another factor that seems to be making a big difference is, as predicted, spectrum specific focus. The e-Shine fixture with 660nm LEDs has been shown, at least in a couple of instances, to equal and somewhat outperform T5HO. The intensity readings I measured seem to support the concept that the LED fixtures tuned to a specific output wavelength provide a much higher amount of useable light for the algae than T5HO, which has a lot of 'wasted' bandwidth. I think it's fair to say you can de-rate the T5HO fixture by 25% and maybe as much as 50%, which, at worst case, put the LED fixture at about double the useful light. Experiments performed long ago (meaning more than 6 months ago) have resulted in similar results (real-life results of algal growth on scrubbers). With this taken into consideration, and incorporating the 'double-light' scrubber, you could likely run an LED fixture such as the e-Shine fixture for half the time that you would need to run the Nova T5HO fixture, meaning the 50,000 hour life would make the fixture last for 14 years instead of 7, if the driver doesn't burn out before then (which it probably would).

So, talking life-cycle cost, the equivalency point of the Nova to the e-Shine, not taking energy savings into account, works out to be about 9 months.

The e-shine fixture runs about $70, plus $75 shipping for 2, and add 3.9% + $0.30 paypal fees that they make you pay when you buy from them bring the cost of 2 fixtures to about $220.

The Nova fixture costs $70 with shipping if you shop around. You will need to buy new lamps, cheapest is 8 for $50 with shipping. So 2 fixtures runs about $140 and 12 lamps about $75, for a total of $215. That would give you the fixtures plus lamps for 270 days. After that, it's going to cost you $100/year in materials (4 lamps x 4 lamp changes per year = 16 lamps @ $50 for 8 lamps). If you compare to the e-Shine fixture at 7 year life, you will have saved over $600 in material cost alone.

This also assumes that the non-waterproof e-Shine fixtures don't fail prematurely due to inadequate construction or lack of appropriate moisture protection by the end user.

As far as energy costs go, I know that the Nova pulls about 57 watts each and the e-shine about 47 watts. So there's not a whole lot of savings there. The LEDs likely pull about 30 watts, add the driver and 2 fans and you're at about 47. However, if you run then half the time per day, and you probably could, then you save 50%. In that case, 2x57 = 114 W * 18 hr = 2 kWh for Nova, 2x47 = 94 W * 9 hr = 0.85 kWh. In CA, that's huge. In Iowa, at $0.07-$0.08/KWh, not so huge.

I haven't ran any numbers to compare CFLs to LEDs but I would expect the life-cycle cost to be a little better for CFL as the initial costs are lower, but using comparable CFL to T5HO wattage, the average and max/min will be much worse for CFL, so I would expect LED to reign supreme.

But, it looks like any way you cut it, LED beats the pants off of fluorescent, hands down. Now it's just figuring out exactly how badly shredded the pants are after the beat-down is over.

[Aeros]

Link is dead.

[Doompie]

Thanks very much for this testing Floyd!!

Realy good approach...

In comparison (how we are getting rubbed here by government) we pay €0,07 cost price, but incl. taxes and "transport" it ends up in €0,27 / Kwh.

My e-shine fixtures are paying themselfs back in comparison to T5's. Not only on materials, but also on power..

I run them 9 hours, and that seems to work.. On 18 they burn my algae.

[Floyd R Turbo]

https://docs.google.com/spreadsheet/ccc?key=0AnHlnR_1kjCldGJpdlYwTC1BampVZWZrS3Z6endKT Xc

Dunno what happened there...

[kaskiles]

If you happen to revive this master plan, maybe use this as a standard fertilizer:
http://florida-aqua-farms.com/secure/agora.cgi?cart_id=5989947.370*pq6xp3&product=MICRO_MACRO_NUTRIENTS

The first one listed is that Guillard F/2 formulation that an earlier poster referenced ( https://ncma.bigelow.org/node/79 ) . They also have a trace pack further down where you add your own Ammonia or Nitrate, and Phosphate. Using these looks like it could get expensive, but they seem to have lots of different options.

[Floyd R Turbo]

Fantastic! Thanks!

[Floyd R Turbo]

After almost 2 years of considering performing this experiment, something dawned on my last night as I was brushing my teeth. I recently performed a large tank move (2nd move of that system within a month) and the result is that the water is high in N and P. No coral in the tank so it's fine. There is even 0.5ppm ammonia but I've been treating the tank with Prime until I get the scrubber going.

So this has been on my mind, and somehow my mind switched over to my scrubber experiment. I have been trying to think of a way to benchmark test various scrubber setups with respect to size of screen, light type, photoperiod, flow rate, etc etc but have been hung up on the source of dirty water. Adding fertilizer to the water seemed OK, but did not seem like a way to get a natural result. Plus, there was the issue of starting out with 'clean' saltwater, which would need to be seeded with some kind of algae somehow. Using a small tank with an few fish and some live rock would be fine, but would not create enough waste for the scrubber, IMO. Then there would be issues with matching the conditions of the water, etc. Nothing seemed to make good sense.

In a fraction of a second last night, it came to me.

The plan now is to set up a large tank with plenty of fish and soft corals or LPS, feed it heavily, and let the nutrients stay elevated. Then, I will save the water removed from this tank during PWCs and put that water into 10 gallon test tanks, which will be running the test unit scrubbers. So now I will have a bank of scrubbers running on small water volumes, and I can monitor nutrient uptake and growth in a more scientific fashion.

The scrubber screens will all be cured up on the same tank, so they will all start out with the same initial conditions, and all with the same algae growing on them. Then the test will be performed.

If I wanted to get really crazy, I could set up an automatic water change system that constantly drips water out of the display tank and into the scrubber tanks, which would then constantly drain the water out of the system (down the drain). This would be how I would be able to monitor growth only, ignoring nutrient uptake. One of the caveats of the first method is that after I pull water from the tank into a small volume, as concentrations of various nutrients decreases, the growth types may shift, which may influence the experiment.

The nice thing is that I have over 600lb of rock to deal with for this experiment, about 200 of which just came out of a tank with uber-high nutrients. I was going to acid bath the stuff but now I might just put it in a tank and let it muck up the water some. Got 2x 5g buckets of sand out of the same tank as well. I also have about 6 L2 units that have mistakes that I have been hanging on to for purposes of this experiment. Now I have a purpose.

Still need the TIME!!

[RkyRickstr]

All sounds good except the part where you seed the screens in the same tank. You should start with a new screen on each set up. We dont know if different light sources grow different types of algae and how they compare to each other.

[Floyd R Turbo]

My plan was to cure all the screens using the same base configuration of lighting, 6x 660nm Red and 2x 440-450nm 1/2 power blues, then when it was time to run the experiments for the different bandwidths, I would scrape the screens down and run that experiment. I imagine that continuing the experiment from that point forward for a number of weeks would eventually result in different types of growth on the isolated scrubbers.

The first step, in my thought process, was to establish a control sequence. I would cure each screen together, then run them in isolation to verify that I was getting identical results on identical isolated systems. After that 'control' experiment was run and verified, I could then proceed to variances between isolated units.

[tebo]

Really it would be a great idea you pose Floyd, really very useful for us

On the other hand you think test, ie the methodology will mesh size versus the light it receives or something

regards

[Floyd R Turbo]

Tebo, are you asking if I could test different types of substrate?

[tebo]

No sorry I misspoke, my English is not very good,,, what I mean is that if you can probe different net sizes and growth under different light intensities