Pulsed flow

[Garf]

Found this, and I'm a bit concerned

http://www.enst.umd.edu/files/KangaDocuments/BioScience Article.pdf

According to the calculations from a single sided, pulsed flow system, these regularly produce 50grammes dry weight (2.5kgs wet weight) growth per square meter per day. Have done an approximation of my growth and it works out at 500grammes wet weight per square meter per day. I think you'll agree, I've got comparatively good growth compared to others. So why is its productivity so low compared to a single side horizontal? The only difference I see is laminar flow compared to pulsed flow. Thoughts please

[Ace25]

I don't think it is really even debatable comparing a surge system vs a constant laminar system. A washing machine comes to mind... take a dirty piece of clothing and hang it then dump water down it vertically, how clean is it going to get compared to putting it is a washing machine where it is agitated? If you can surge an algae bed it seems like that would be a comparable situation. It will keep the algae free from detritus and deliver nutrients much more efficiently in a surge system. Problem is designing such a system to be quiet, compact, and fail proof, all while still trying to maintain a steady water level so you can still use an auto top off system for freshwater.

I had a new design in my head over the past week from the conversations on here for a new ATS, I was planning on starting it today... until this thread.. now my mind is racing in a different direction to try and figure out the solutions to the above problems I listed. I think the obvious answer is it would have to be done in a 3rd tank, like a separate refugium, where you can provide a surge without affecting the water level in the display or sump.

[Garf]

We will come up with some sort of test rig, I'm sure. :)

[Garf]

Seems like the most efficient simulation of the Hydromentia pulse flow, would be a flooding waterfall box, with an auto syphon. Bugger, I ain't got a box.

[Floyd R Turbo]

I toyed around with the idea of the surge scrubber a while back, my thought was to incorporate the use of a CSS (Carlson Surge System) and a waterfall scrubber, but that would require the CSS to be ancillary or very quickly filling, and then the issue is that the scrubber is only filtering when the water is surging across it.

The other thing to consider is that the 2.5 kg/day figure is likely possible due to the presence of waste to be consumed, could be different algaes (freshwater, specifically, for wastewater treatment), plus that figure of 50-60 g/m^2/day was in June/July in California, then only 8-12 in December.

I recall recently someone posting an extremely large waterfall scrubber that filled up with water then purged out. This is the opposite of what you would actually want, you would want the surge to flow across the screen, not to drain the now submerged screen.

The CSS/waterfall would mean you would need a lot of space, and yes likely a separate tank, two actually. One to fill up and act as the surge source, the other for the scrubber to drain into, and you would still have level issues with the ATO.

I think the biggest issue is that we are polishing saltwater for corals and fish to live in. Wastewater treatment plant (WWTP) scrubbers are cleaning up grey water (WWTP effluent) so that it can be purged into a river/stream and meet government guideline for safety. big, big difference

[Garf]

In the link (I think it's the one I posted) nitrate and phos levels can get down to 10 parts per billion, before limitation occurs. Been reading some stuff on this and it seems that one of the the main benefits is from the movement of the algae exposing itself to light. I'm gonna try it with an old skimmer, tiny slot tube, Perspex window frame for the screen, aerated down the screen, might be able to do double sided, auto syphon. I've got nearly all the bits so not gonna cost anything to try. The benchmark would be bettering the 0.222 g/sq inch/day im getting now. If the figures in the report are accurate, and I've interpreted it right, the screen would only need to be 1/4 of the current size, harvested every 5 days. Seems a bit too good to be true. ;)

[Floyd R Turbo]

Why not just get a variable speed pump and ramp the flow up and down like a wavemaker? DC pumps would be good to use for this. Also something to consider would be a wider slot on a slot pipe that would be able to handle intermittent flow at much higher rates

[Garf]

Why not just get a variable speed pump and ramp the flow up and down like a wavemaker? DC pumps would be good to use for this. Also something to consider would be a wider slot on a slot pipe that would be able to handle intermittent flow at much higher rates

Wider slot, yep gonna try that.

[Garf]

Floyd - you still got a UAS running ain't ya. You could try reversing the flow. The UAS is obviously uni directional, but it needn't be. You could run the water flow so the circulation rotates one way, then run vigorous bubbles intermittently to reverse the flow. Seems like it would be exactly the effect of an intermittent surge. I'm not a subscriber to the notion that the bubbles rubbing the algae is the key (the algae is never dry when a bubble rubs against it) but bubbles could be used to reverse flow. Or run two sets of bubbles on timers, sometime the flow will be up, sometimes flowing down, sometimes chaotic. I'm thinking about buying into the UAS if run logically with reference to this thread.

[Floyd R Turbo]

Well that one scrubber build that had the skimmer pump blowing water through a chamber with the screen flopping in it like a flag would be the closest to what you are getting at. Maybe something along those lines. I have been searching all over for the thread with that particular build in it. Anyone remember it?

[Garf]

I think I recall it. However Adey clearly states in other research that it's to back and forth motion that spurs growth. I think the skimmer would be minimum back and forth, maximum chaotic. Gotta watch out for bubble density also as skimmer ish bubbles would reflect, deflect lots of light. Looking at Adeys stuff a 1 inch layer of water against the screen is ideal.

[sklywag]

What if you built it just under water surface or at surface and use one of those Tunze wave boxes? Would take a large sump and those boxes aren't cheap. But some of you seem to have money trees in the backyard.

[Floyd R Turbo]

Ok, 2 ideas:

1) A standard waterfall scrubber with a secondary inlet on the bottom/side that ties into the dump chamber of a CSS. The waterfall operates 24/7, and the surge from the CSS fills up the scrubber box temporarily, but very quickly. This action would lift the algae up and move it all around, then it would quickly drain/purge from the box and the cycle would repeat. Probably 60 seconds between surges maybe, depends on how big of a surge is needed to temporarily overwhelm the drain(s) of the scrubber box, and how big the pump is that feeds the CSS.

2) A submerged flag screen (still can't find that thread!!!) that has a bubbler along the bottom of the box under the screen, and inlet from both sides, tied to a SCWD or similar device.

I would try these, but right now my money tree is funding my need to dig down to the foundation of my house to find out why it is not draining properly, which results in 1500g of water in our basement after 3 days of rain every spring.

[tebo]

When making my sump change, got a ats in a side of the tank to the top, i connect With This SCWD
This gave the water on ats every 60 seconds, With intervals of 60 seconds
then really did not pay much attention to it, but if I can notice a Greater growth in the alga full month during That happened on the tank

http://i1043.photobucket.com/albums/b440/tebomarino/DSC02575.jpg (http://s1043.photobucket.com/user/tebomarino/media/DSC02575.jpg.html)
http://i1043.photobucket.com/albums/b440/tebomarino/DSC02574.jpg (http://s1043.photobucket.com/user/tebomarino/media/DSC02574.jpg.html)
http://i1043.photobucket.com/albums/b440/tebomarino/DSC02578.jpg (http://s1043.photobucket.com/user/tebomarino/media/DSC02578.jpg.html)

Saludos

[Garf]

Has anyone dared to use a paint roller tray, for a horizontal screen base. I'm thinking about using the flow of my waterfall to provide laminar flow, but with a "bubble box" stuck underneath it to provide a bit of opposing flow which should cause turbulence. I've been looking at an old screen I've had in the sump and about an inch under the water algae growth is phenomenal. It's actually covered the surface of the sump behind my waterfall screen. Basically I think I'm gonna put a horizontal underneath my waterfall and see if the change in environment causes different growth, diversity.

[Ace25]

Tebo, I would HIGHLY recommend you moving that computer power supply away from the water. They are not sealed and will pull it humid salt air easily. That picture scares the crap out of me. I don't think I would be able to sleep at night out of fear of a fire starting. The meanwell driver is fine.

[sklywag]

When all the hype of the UAS came out and I almost got caught up in it. I was thinking of using one for it. I have a very sturdy plastic one and thought that the slant against the glas would force the air and water through the algae more. Also being wider at the bottom would have allowed me to put my drain righ into the bottom of it filtering all the water from overflow.
I keep thinking about a horizontal because it's much easier for me to make it quieter than my waterfall method and seem to get the same amount of growth from either.

[Ace25]

I think a 'simple' method for making a horizontal that works decent would be to put 2 small powerheads on each end of the tray and use something like a Hydor controller so the powerheads pulse back and forth. Seems easier and quieter than using a dump style setup, although more costly. Thinking about it a little more, if you placed the powerheads on the outside of the tray and the bottom of the tray is flush with the surface of the water in the sump, you could drill a hole in each end of the tray for the powerhead to stick through (thinking a MJ1200 style powerhead) and put a small PVC manifold on each end/inside the tray to spread the flow out evenly. The water would then just overflow over the top of the tray into the sump, and if the walls of the tray are only an 1" tall or so it should still be almost silent. Just throwing out ideas as they enter my head. LOL

Back to Tebo's pictures.. is that your sump in the pictures? If so, how do you handle power outages/sump from overflowing?

[Garf]

I was gonna have it float under the waterfall, but SM posted a floating scrubber so decided not to go down that route yet and have it fixed. Perhaps the bubbles off my waterfall screen will give some turbulence. Only one way to find out I suppose ;)

[RkyRickstr]

Would a solenoid valve on the drain work?

[Floyd R Turbo]

I don't think so, at least not IMO. The purpose is not to stop and start the flow as it is to reverse the flow direction, or increase the flow dramatically. For the latter, it might work to have a secondary pump that is cycled on and off, but this would not account for the directional reversing.

What about a combination of the waterfall standard slot pipe and a spray bar like acorral uses on his scrubbers, except more randomized hole placement, then one could turn that spray bar pump on and off to break up the growth pattern? I'm thinking of something funny now, our kids have a sprinkler that they play in that has a bunch of rubber hose sections that flail back and forth...like this http://www.sears.com/sports-and-toys-by-o-discovery-kids-outdoor/p-SPM6403684008?PDP_REDIRECT=false&s_tnt=39869:4:0

[kerry]

I am sure I have not read every thread since I have been away but, just my 2 cents.
My horizontal scrubber in my pod tank has always been a semi floating deal (half of the horizontal ramp is in the water) but I never thought anyone would build one. Floyd calls it the blob LOL. It works better then a horizontal that is out of the water but surely falls short of a water fall type.
Kerry

[Devs]

I think this is a good idea but, instead of thinking around a horizontal screen, I think it would be better to evolve around a vertical screen. Something like...

- Screen sits inside chamber with an inch clearance from both faces, the chamber has a bottom feed in on one end and similar feed out on the other. How you supply the feed in and dump it out is what needs a bit of thought.

This may have already been mentioned but I've not scrutinised this thread :)

[cdm2012]

I have a freshwater system and I put together a small CSS algae scrubber. The water feeds in via my overflow and once it fills almost to the top with water the water is then surged out rapidly. It also has an air pump on it running bubbles along the screen. I made it so the bubbles could run across the front of the screen or the back of it. Right now I have it the bubbles running along the back side until I come up with a way to hide the air-holes so they don't get filled with algae.

43044305430643074308

It works like a charm but it does produce a lot of bubbles when it surges into the sump. I have reduced that by placing a cup underneath the output pipe and covered the top of it with screen material. The majority of the bubbles get broken up by the screen and dissipate along the surface.

It fills up to about 80% allowing the water to completely cover the algae screen. I figure it is only filling about a half a gallons worth of water, so it doesn't affect the sump level too much. I don't use an ATO, but I could see where there would be a problem if I were to use a bigger container.

Any thoughts on this build...pro's and cons?

[Garf]

I love it. That's exactly the idea I've been toying with. Now I know it can be made to work, ive got renewed confidence. What lighting you got on it, and what is the surge pipe made from, and what flow is going into it? The only things I would do different is make it double sided by having the surge pipe further away from the screen, make it thinner so theres only an inch or so of water between the screen and the container wall, and get the water to enter the container through a slot pipe that holds the screen so the screen has heavy flow when the surge is discharging and recharging. If I can get one of these to operate correctly I could get it to discharge onto my horizontal and provide exactly the surge that Adey suggests is required.

[Ace25]

Great design cdm2012! Only issue I see which you already mentioned, is using it with an ATO on the system.

[Floyd R Turbo]

I think what it all comes down to is this: when is the filter filtering?

The answer is: when the water is moving across the substrate.

This is the crux of all algal filtration systems.

For the horizontal scrubber, dump-style, it filters when the water rushing past the screen. So when the tray is filling up, there is some filtering as the water is in the process of submerging the growth, but it isn't until the dump happens that the water is rushing past it. Recent discussions about the efficiency of horizontal scrubbers (here and on RC, an a few references on Inland Aquatics' site) have brought up the supposed fact that true turf algae has a nutrient fixing ability 10 to 100 times that of other photosynthetic organisms, including GHA. I haven't looked into turf much and ashamedly haven't read Dynamic Aquaria, so with that being said, the fact that the vertical scrubber always has water running across it makes it a different system...

For the vertical scrubber, waterfall type, this is under constant flow.

For the upflow scrubber, the bubbles provide the motion for randomness but the water flow is low, which is IMO it's downfall. Could be the same problem for the floater, but I'll wait until the marketing hype is over and we actually see the product.

But, back to the OT, I think that the issue (potentially) with yours is that it is only filtering when the screen is underwater and the bubbles are causing the random motion. When it is surging out, there is some motion there as well, but it's not really surging past the algae as it is draining off of it.

I'm not saying that it's not working - it obviously is!! The "pro" might be that there is a benefit in the fill/drain/repeat process that keeps the algae changing positions and does not allow for air pockets to stay formed. On my UAS, once the bubble bar gets clogged (only a few days in) then the screen is covered in air bubbles, it looks like little eyes everywhere - kinda creepy actually.

I think that the ideal combination of a surge and waterfall would be a CSS that dumps into the bottom of a waterfall chamber. I think of one of my L series scrubbers with a third drain on one side, so that the scrubber is normally operating as any waterfall scrubber would, but then the CSS would surge and fill the box up completely, and then the emergency/secondary drain would purge out the surge. This would have the effect of temporarily filling the box and breaking up any structure that would form and trap air or mat over growth, etc. The period between surges could be rather long, as it is not really necessary for the filtration to be effective - rather, it would be just a means of performing a secondary function of breaking up the "monotony" of a constant waterfall flow.

EDIT: I seem to be repeating myself...for anyone reading this entire thread...sorry!! I said this all once already!

[cdm2012]

Thanks Garf. Build info: The screen is 3.5"X7.5" (roughly 26 sq in). I feed 1 cube of food a day.

My lighting right now is a 23w cfl. But I want to change to LED's or an LED bulb in the near future.

Right now my flow into the scrubber is close to 120 gallons an hour.

It takes about 15 seconds for the unit to fill and about 6 seconds to surge out.

The Carlson is made out of 1 inch PVC.

[cdm2012]

Thanks Ace! And thanks for the comments Floyd!

Floyd, you mentioned that the only time the filter is filtering is when water is moving across the substrate. Does it have to be moving rapidly? When the filter is draining, water still remains on the screen, albeit it is a thin layer of water, but it is not dry. In fact, you can still see water slowly draining downwards due to gravity until it refills (which it does rather quickly). I'm assuming that it is still doing some filtering and in addition, I believe exposing it to the air might allow the algae to encounter some CO2.

[Floyd R Turbo]

I would be talking out of my rear if I said that air exposure did or did not affect CO2 uptake of algae, so I guess I can't really answer that one...someone else might know.

I would venture to throw out an educated guess that even though there is some water still draining off the screen as the CSS drain the box, the effective filtration would be a function of the rate of flow, so as less and less water is actually clinging on to the screen in the process of draining, the effective filtration would drop at a rate that was close to the amount of water left on the screen. I would think that would probably be something that is close to impossible to actually measure, even with good scientific equipment, because we're talking about a snapshot in time of the primary production process.

[cdm2012]

I hear ya. From what I can tell so far, is it seems to have a lot more flow across the screen than a standard UAS, which is what I like. But of course, it has only been in operation for 24 hours (the screen is from my one sided waterfall that I cleaned off yesterday). I'm excited to see what kind of results I get over the next week or so.

Another possible issue that I'm going to monitor is the lighting period. Currently I run my cfl 18 hours on and 6 hours off. Being that there are a few seconds of no rushing water on the screen (exposing it to direct light) I'm hoping the light does not burn the algae. I might have to reduce the hours or maybe even the wattage. But this is all conjecture right now.

[Devs]

This is what I had in mind on post 23...Nice job :)


I have a freshwater system and I put together a small CSS algae scrubber. The water feeds in via my overflow and once it fills almost to the top with water the water is then surged out rapidly. It also has an air pump on it running bubbles along the screen. I made it so the bubbles could run across the front of the screen or the back of it. Right now I have it the bubbles running along the back side until I come up with a way to hide the air-holes so they don't get filled with algae.

It works like a charm but it does produce a lot of bubbles when it surges into the sump. I have reduced that by placing a cup underneath the output pipe and covered the top of it with screen material. The majority of the bubbles get broken up by the screen and dissipate along the surface.

It fills up to about 80% allowing the water to completely cover the algae screen. I figure it is only filling about a half a gallons worth of water, so it doesn't affect the sump level too much. I don't use an ATO, but I could see where there would be a problem if I were to use a bigger container.

Any thoughts on this build...pro's and cons?

[Floyd R Turbo]

Well it will be interesting to see, I did not realize that you took this off a waterfall scrubber, I thought it was in operation like this for a while....

[cdm2012]

Thanks Dev!

Floyd, do you think I should start with a fresh new screen so we can monitor the results more accurately? I've got one ready to go!

[Floyd R Turbo]

I think you're fine. You can always try that at a later date.

[cdm2012]

I've been doing some additional research on Carlson Surge Systems and ATO's. Here is a quote that I found over on reefcentral.com: "
Mount the float switch in your sump level with the water when the surge tank is full. When the S tank dumps, water in the tank/sump will rise which wont hurt anything, and when the S tank fills up again, the float switch should still be up. When water evaporates, the auto top off will kick in when the sump water level is the lowest and the surge tank is nearly full. It might come on a little more frequent but it will still work good.

I've also noticed that most that are using CSS's are using them to create a surge effect and they want to move a lot of water so they use large containers with many gallons. I think if used with an algae scrubber you don't need a huge amount of water. So the sump level shouldn't rise too high or too low, although it will fluctuate to some degree.

[Floyd R Turbo]

This thought had also crossed my mind, regarding ATO function. With a low-volume, long-cycle CSS, the ATO would function a little better I would think. There would be a longer period of time when the box is full.

However something just popped into my head that may thwart my thought process on one of my units. The outlet of the CSS has to be underwater, does it not? Otherwise, the siphon wouldn't actually start and flush out the surge source container. This would be a problem in my unit because of the false bottom, I think a special scrubber body would need to be made to make this work right, extra space for the surge pipe or something.

[Garf]

This is how far I got with my effort, a few weeks back. Was gonna try and put the surge pipe in the back, make a partition for the screen to make the tank thinner and feed it with a wide slot pipe, but as you can see, never got far with it;

http://i1269.photobucket.com/albums/jj597/Garf1971/d0f13737127144e03bc260e0ba28dee6_zps7cb6a9cc.jpg

[cdm2012]

Yes, it has to be under the water.

Something else I found out in my case is that if the outlet was too deep into the sump it wouldn't work. This caused the water level in the scrubber to keep rising and it overflowed. So that is another reason why I have the outlet go into a cup. It maintains a constant water level no matter what level the sump is.

I also discovered that you have to have the correct level for the intake pipe as well. I experimented with letting the water pour in from the very top but when the water level was low in the unit, the water splashing noise was loud, PLUS the siphon would not start for some reason once it filled up with water. But when I placed the intake half-way down the unit or put it near the bottom the water rises quietly and the siphon starts every time. It took a little experimenting to get it working correctly, but once it did, it worked flawlessly.

But I'm wondering if a waterfall CSS could be made having water come in via the intake across a slotted pipe with an algae screen. With what I found, I don't think it would, so hopefully someone tries it to find out if that is possible.

But I'm sure you could easily run one off the outlet pipe but this would require 2 units one on top of each other. One for the CSS and the other for the algae scrubber. Hmm.....

[Garf]

The fact that the surge tube needs to be submerged is something I had forgot. I tried it with a chopped up old skimmer and it would surge for a few minutes then stop. However the end of the tube was not submerged. I've still got the bits for that, so that's another option I've got :)

[cdm2012]

The fact that the surge tube needs to be submerged is something I had forgot. I tried it with a chopped up old skimmer and it would surge for a few minutes then stop. However the end of the tube was not submerged. I've still got the bits for that, so that's another option I've got :)

Nice!

[Floyd R Turbo]

Technically, I don't think the outlet pipe really needs to be submerged, but it definitely needs to be lower than the "high" water level, and then it must be able to close off flow and become a full siphon. This might be achieved by putting a reducer on the outlet so that when flow starts, it seals off the pipe and then starts to purge the air from the pipe.

[Garf]

Has anyone noticed an upsurge in interest for horizontal scrubbers since this statement a month ago?


Pulsed flow
Found this, and I'm a bit concerned

http://www.enst.umd.edu/files/KangaD...ce Article.pdf (http://www.enst.umd.edu/files/KangaDocuments/BioScience%20Article.pdf)

According to the calculations from a single sided, pulsed flow system, these regularly produce 50grammes dry weight (2.5kgs wet weight) growth per square meter per day. Have done an approximation of my growth and it works out at 500grammes wet weight per square meter per day. I think you'll agree, I've got comparatively good growth compared to others. So why is its productivity so low compared to a single side horizontal? The only difference I see is laminar flow compared to pulsed flow. Thoughts please



Post#1

[Floyd R Turbo]

Well it certainly has piqued my interest. I think all of this forward progress made in the last 5 years or so warrants taking a step back and asking some fundamental questions. Plus, I'm going to order Dynamic Aquaria and read it finally.

[Garf]

Right, got my pulsed flow set up working. Its a Horizontal and it'll soon have a couple of special features including a laminar flow baffle plate, special 3D screen and adjustable screen height platform,just for starters. :)

[Pny]

Right, got my pulsed flow set up working. Its a Horizontal and it'll soon have a couple of special features including a laminar flow baffle plate, special 3D screen and adjustable screen height platform,just for starters. :)

Any news of this?

[Floyd R Turbo]

Not on here, see the "banned" under Garf's name? you can find him on my site if you want to contact him about what he's working on.

[RkyRickstr]

Why in the world would a person who has contributed so much to this hobby and this forum get banned?????????????