Screen lighting

[kcress]

Light Color.

What is the best color? Do we actually know? The white CFLs seem to work pretty well, but I have seen red and blue bantered about. Anyone know exactly which red or blue?

[SantaMonica]

Most seem to work well. My acrylic uses 3000K on one side, and 6500K on other. I have trouble telling the difference.

[worley]

I personally found 3000k lights pretty poor and have had much better results from 6500k lights, however the 6500k bulbs themselves seemed to produce more light (same wattage, different style, different manufacturer).
In general I've notice much more algae growth in various tanks under 20000k MH bulbs than under lots of lower colour temp tubes, even if they produce similar amounts of light, so again it would suggest better growth from higher colour temps.

[worley]

Hmm, had a thought.
I think the reason they use red and blue LEDs for growing plants must be because they're aiming it only at green leaves, so the green light is reflected and not absorbed, therefore wasted. Higher colour temp bulbs are producing slightly better growth as they have more blue in the light.
I would also guess that with red/blue LEDs you'll probably find that certain different coloured algae doesn't grow as well, e.g. the darker browns, as they would absorb more of the spectrum.
However, it would be a complete waste getting bulbs (non-LED) that are coated with a colour as the coating simply absorbs the other colours, I believe LEDs actually produce the right colour spectrum without needing colourings (could be wrong, as red LEDs are in red plastic most of the time).

[SantaMonica]

Actually all algae and plants use primarily red and blue only, since that's what chlorophyll A and chlorophyll B use. They don't use green, and they don't use "white". That's why plant-grow LEDs are only reds and blues. The product the algae and plants grow, however, looks green.

[kcress]

Ah the A/B thing. All those higher temp bulbs do put out way more blue. I had just never really seen blue lights used in growing applications of plants. The blue and red seemed strange to me since I would think one or the other not both Maybe the A/B thing.

Of course the reason I ask is because making a LED panel for a screen allows one to pick specific colors of about any shade with only certain colors utterly unavailable. I'd rather use just the color desired by the algae of interest.

Perhaps a test will be needed. <Sigh>

[worley]

That was my point Santa :D
White light is a mixture of RGB (red green blue), so the green is wasted as it's reflected and not absorbed, but as not all algae is green, and some is technically bacteria, I guess they don't all use chlorophyll.
Still want to find out if red LEDs actually emit red light without the red plastic around them, if so, they're just as inefficient as white LEDs for this purpose.

[kcress]

Still want to find out if red LEDs actually emit red light without the red plastic around them, if so, they're just as inefficient as white LEDs for this purpose.

Sorry now I understand your question.

All LEDs with the exception of white put out the color you see. The only reason some are in colored plastic is so they themselves light up when energized. Colored ones are used to "indicate" as apposed to "illuminate".

[cvermeulen]

Been doing a bunch of research on this topic. Here is an excellent and very detailed article on bulb comparison for planted aquaria: http://www.aquabotanic.com/lightcompare.htm. Apparently regular daylight fluorescents from phillips at 5000k are the best, but basically, the brighter the better. (And Lumens aren't necessarily the best indicator of light energy output).

[kcress]

cvermeulen; That was exactly what I was looking for!

Many thanks!

[Patrick Pending]

My first post here so, hi everyone.


Actually all algae and plants use primarily red and blue only, since that's what chlorophyll A and chlorophyll B use. They don't use green ...
- that's correct (except for the green bit, and my apologies in advance for being picky :oops: ) Chlorophyll A and B both have peaks in the photosynthetic response curve in the red and blue area of the spectrum. However, there is also a measurable (albeit, smaller) response in the green area of the spectrum. In rain forests much of the light filtering down from the canopy is green and the forest floor plants (and algae) still manage to grow. Having said that, I am not sure we should view marine algae in quite the same light ;) as plants.

light does not penetrate well in seawater. Red light penetrates very poorly, green light does a little better and blue light is better still. Naturally the algae have adapted to what light is available to them at the depths that they grow. So, you will find algae that grow well for any colour of light - wherever there is a niche there is an algae to take advantage of it. I believe, some algae utilise Chlorophyll C which has a peak spectral response to green light :idea: this is why I was being picky about the green :idea: So, it could be that green light is actually useful for growing algae. :o

I am by no means an expert in this field and am happy to be corrected. I am just curious to what type of lighting is best, and most efficient, for a scrubber. I am presently using CFL's with 6500k(cool white) on one side and 2700k (warm white) on the other. After about 3 weeks of running my scrubber the warm white currently has better growth on it. The question is though, is it the right sort of algae? - time will tell.

[SantaMonica]

All algae is the right algae, when it comes to removing N and P. Red/brown turf is nice because it's so compact, but all algae do the job. After several months of testing 3000K on one side of my screen, and 6500K on the other, I'm now convinced that 3000K is better and I just ordered all 3000K replacement bulbs.

And after several test of 14K halides, I'm convinced they are not nearly as effective at growing algae, regardless of their power.

[worley]

That's really interesting, I seemed to remember you having higher growth initially on the 6500k side from your photos, has it changed now?
I can say that the 6500k bulbs I have are producing considerably better growth than the 3000k ones I had before, however they are different brands and different styles but similar power. I think it's probably just that my 6500k bulbs appear much brighter visually than the 3000k bulbs, and aren't hampered by diffusers.
I may replace one side of mine with 3000k PL-L bulbs and see if it makes any difference too.

[SantaMonica]

Was not a big difference, but after turning the screen around several times, the 3000 side always had bigger lumps at the end of the week.

[Patrick Pending]

I think different lighting will favour different types of algae - it depends on what types of algae you have whether a particular light works well with them.
Many algae do not contain chlorophyll B which would mean that much of the light between 2500K and 6000k (650nm - 450nm) would be wasted on them. The phosphors used on CFL's only produce peaks at particular wavelengths (despite their claims!) those peaks may miss completely the wavelength required by the particular chlorophyll. Many plant grow lights (and LED grow lights) put out light at about 460nm this is great for plants with chlorophyll B but will have no effect on chlorophyll a. I am sure you can grow algae with any type of light. However, if you want to favour a particular type e.g., red turf (macro algae) then only providing the specific wavelengths required by that type should cut down on the slime, diatoms, undesirable algae etc.

I think that the most efficient way of of lighting an ATS may be with LEDs. LEDs are virtually monochromatic so you can target the peak wavelengths of the chlorophyll* (for chlorophyll A that would be blues at ~430nm and reds at ~680nm). There are several advantages to using LEDs in this application:


low voltage (safety!)
even light distrubution over whole of screen
high lumen/Watt efficiency
low heat output
long life (10 years)
compact
~monochromatic (no wasted wavelengths produced)


Providing you make the LED panel waterproof then you could place it very close to the turf so you might get away with relatively low power LEDs.

* other photosynthetic mechanism are used in addition to chlorophyll

Cheers,

Pat. Pending

[SantaMonica]

Where might be a good place to find what wavelength corresponds to which algae?

As for the proximity of LEDs to the algae, did you see this?...

viewtopic.php?f=3&t=34 (http://www.algaescrubber.net/forums/viewtopic.php?f=3&t=34)

[Patrick Pending]

Where might be a good place to find what wavelength corresponds to which algae?I gleaned all my new found knowledge about algae on the Web. The trouble is it is just snippets within biological papers and unfortunately, the vast majority of the information has no relevance to our particular application. It does take a lot of wading through to get anything useful. I think I have learned enough to pull together a summary of the different algae types and their required wavelengths. I will have a bash at it tomorrow and post it here.


As for the proximity of LEDs to the algae, did you see this?... No, I hadn't, Interesting though. Clearly, to take advantage of the inverse-square law (WRT light intensity) you need a high concentration of LEDs. LEDs have a relatively narrow cone of illumination. So, if you want to move the panel close to the algae whilst avoiding dead spots you need to have them close enough together.

Cheers,

Pat. Pending

[SantaMonica]

Yes I'm thinking of .5" separation, with a prismed flat-sheet for diffusion. An advantage of closer placement (and more LEDs) is each one is lower power (and cheaper), but more soldering.

[Patrick Pending]

My original thoughts were, a thin sheet of acrylic drilled (pegboard style) for the leds to stick through. Nothing in front of the LED lens as this would reduce the main light output. Once the LEDs are inserted into the acrylic the back of the acylic panel, along with the back of the LEDs, gets painted white to reflect any stray light forward.

When I can get round to it (also when I can remember how to use steradians) :roll: I will do the math and work out the numbers of LEDs required and their specification.

Cheers,

Pat. Pending

[SantaMonica]

So you are saying that the LEDs would not go through the acrylic, but would just be inserted into it? That might be easier than pouring liquid resin over a PCB, but would not be as thin (for two-sided.) I still think you'd need a prism diffusion sheet, unless each LED had a very wide luminence angle. The only LED testing we have so far is Snail's, who only had growth where the red and blue LED's overlapped.

[snail]

Did I hear someone call my name? :lol:

http://greenpinelane.com/lights_main_menu.aspx

http://photoscience.la.asu.edu/PHOTOSYN ... INTRO.HTML (http://photoscience.la.asu.edu/PHOTOSYN/EDUCATION/PHOTOINTRO.HTML)

These links may have been posted already.

I have spoke with an LED manufacturer via email and have been assured that the spectrum of red and blue with 30º angle and 5mm are specifically designed for grow applications.

As SM has mentioned, getting the overlapping rays for the synergetic blend is the trick.

In first link, it shows the effectiveness at different distances.

The prism diffuser holds the best promise thus far. In the second pic you can see where I set a regular fluorescent light diffuser panel. Typical Home depot stuff.

first pic is the growth after about a week. I recently shut down the surge, as the algae was washing off the screen.

[snail]

So if you note the major growth area, this all happens at a distance of over 5" from the grow panel. Individual bulbs are spaced about 1" apart. With the addition of the small chunk of diffuser, you can see the green section above the main growth, this was not there prior to adding the difuser, which now allows growth closer to the lights.

You can pack the led's closer to eachother I guess, but in close to the light, the led will only spread 1/4 of an inch or so and you still will not see the overlap needed for growth. Unless you back the led panel away to the optimal 5 inches, you do not get the balance of blue red required.


Moving the lights in closer, putting more lights per square inch and using the diffuser, looks to be the best so far.

And here is a link to a UTUBE of my fishy eze :lol: http://www.youtube.com/watch?v=3RIbQnjLMcQ And thy say it can't be done LOL. I plan on packing this tank with fish so I can get a max bioload on it. Looking for maybe a snowflake eel and maybe a niger trigger. That should stress out the tank :shock:

maybe even load the sump with critters.

[kcress]

The acrylic with non-thru holes is exactly what I'm building.

And with lots of LEDs.

I will route the face of the panel so the light is diffused and the turf has handholds.

Being an EE I can't go with simple AC LED driving methods that wastes the LED capabilities horribly, like most of the off-the-shelf panels. I'll be using a LED current control circuit designed for back-lighting of LCD panels in laptops and flat panel displays. The control board will be integrated into the panel in a routed relieved area. Any cooling needed will be provided by the water flow. For a first pass I will probably just do it one sided. Two sided would basically be two panels back-to-back. I believe a two sided unit could be about 5/8" thick. Power would be from a cord-wart, 12 or 24VDC, (not sure which yet). The prototype will have dimming ability in case the results are too bright unless you guys think that's impossible(it is big a hassle).

My plan is to use LEDs that are right at the spectral peaks of the activation curve for photosynthesis. I'd mix them in different groupings, and with wide spectrum insanely bright white units to see if there is any need for white and to see if turf has a big preference to red or blue or needs none of, say, red.

I live by the ocean, (Monterey Bay Marine Sanctuary), and was contemplating floating something in the bay to start the turf, but then I would need to transfer it to the panel somehow. Not sure it's worth the hassle.

I will run the scrubber on my 165gal sumpless tank which currently is hovering around 1100ppm nitrate, and ??? phosphate,(need a kit - got a suggestion?), and looks like a graduate study in algae types. I am letting the pods clean the glass which they do weekly in crowds of tens of thousands. They are better than any snails as they bring it down to clean.

Can we at this point definitively say that we need blue and red? Sounds like it.

Can we definitively say we do not need any white?

[consigliere]

As I stated in one of my other posts : I found the GE 9325 k 55watt pc bulbs to produce excellent growth...give them a try !

[snail]

kcress- my panel does not have white led in it. I do not know if it is giving optimal growth, but I have not tried with any other light source.

For powering your panel, why not use a phone adaptor or any other 12 volt dc power supply? That would keep the tranformer etc outside the tank, outside the lite panel.


That is how mine will be powered, like my eclipse hood and my glow t-5 ballast.

consigliere--The led is a lower energy use light source. Also less heat is produce. This is why I am experimenting with LED vs other proven light source.

As been mentioned I may be the first to use led on a scrubber. I can attest to phenomenal growth when used directly on my sump with macro using led panel. The way this sump is set up and how my scrubber is positioned, I am having difficulty using the correct position of lighting for use. I had built the sump with using lots of macro and the led panel.
I also made provisions for the skimmer, but if I don't need one, heck, my 225 will be set up scrubber style.

This however has opened up discussion on light positioning and overlap for optimal growth. Maybe the led cannot work close in ever. But with diffusers now maybe they will. This lends to the compact configurations teh 3rd generation brings about.

But also you bring great ideas to mind. Suppose a company produced a specific light fixture to facilitate the gen 3 design.

A submersible waffle compact fluorescent. But then heat is still the issue here. The bulb requires heat to run, and the water flowing would cool it to less than optimal running temp. This could skew the spectrum. And also heat the water more which is not desirable.

[kcress]

Hi snail.

A 'cord wart' IS just a power adapter. Like a laptop computer adapter.

I cannot in good conscious just use an adapter. LEDs are constant current devices. Using just a DC supply requires an inefficient resistor and allows no automatic adjustment of the required current. Furthermore if an LED in a series string of them shorts, which is not uncommon, and you have no current controller, the power goes up dramatically, and can lead to a fire.

[snail]

Hmmm constant current regulator circuit, shouldn't be too expensive or complicated.

The one inside my light panel is quite small and relatively few components. I can always borrow some circuit ideas from that.

I just figured the led would pull the current it needed and that was all. If less is delivered it just gets dimmer, so I guess your are saying and led can be overdriven even at a constant voltage?

Good to know before blowing out a bank full

[kcress]

I just figured the led would pull the current it needed and that was all.

Absolutely false! Not even vaguely correct. A common error too. :D

LEDs are not like light bulbs that are variable resistance devices that you supply a voltage, they heat up gaining resistance until equilibrium is reached and the current becomes constant. LEDs represent only a temperature related voltage drop. To get the LEDs on you need a voltage source who's voltage exceeds the series total of the various LED voltages comprising your string. Once that occurs the LEDs can light up. However they have NO mechanism for limiting the current. Any tiny change in voltage will result in a massive change in current. If the change exceeds a total current of 20mA for the LEDs we are contemplating they will fry in moments. A resistor can be used as the current limiter. Everything across it is wasted as heat. It can't tell if one of the LEDs shorts and safely turn the rest off or change its value to compensate.

These cheap LED panels we're talking about use just a resistor and sometimes a rectifier and perhaps a capacitor to limit the current. To prevent fires they often have to severely limit the current down from the normal running level. This means the LEDs will be much dimmer than necessary.

[SantaMonica]

No white is needed. Otherwise plant grow LEDs would be using them.

As for close-placement, wide-angle LEDs should be used... they are 120 degrees, instead of 30 degrees. This, in combination with a prism layer, might do the trick. Here are some prism sheets:

http://www.anchoroptics.com/catalog/product.cfm?id=311

keywords for further searching:

diffuser film
prism film
optical film


links I found:

http://www.optigrafix.com/light_diffuser_film.htm
http://www.alibaba.com/product-free/104 ... plate.html (http://www.alibaba.com/product-free/104154826/prism_film_diffusion_plate.html)
http://www.suntech-web.jp/pdf/suncrysta_2008.pdf
http://cgi.ebay.com/LC-40c37u-Sharp-Aqu ... 18Q2el1247 (http://cgi.ebay.com/LC-40c37u-Sharp-Aquos-LCD-back-lighting-and-diffusers_W0QQitemZ290214272762QQihZ019QQcategoryZ 3320QQssPageNameZWD1VQQrdZ1QQcmdZViewItemQQ_trksid Zp1638Q2em118Q2el1247)
http://www.alibaba.com/product-free/101 ... image.html (http://www.alibaba.com/product-free/101271682/Prism_sheet_optical_Film/showimage.html)
http://www.laserfocusworld.com/display_ ... ook-better (http://www.laserfocusworld.com/display_article/305702/12/none/none/News/FLAT-PANEL-DISPLAYS:-Wavy-prism-sheet-makes-LCDs-look-better)

[snail]

SM, if those diffuser sheets came in thick sections, they could be used for the housing. Most of the stuff I have seen is very brittle however, and that would not be cool if you cracked it while submerged. So the next best is to laminate a thin sheet onto the acrylic screen housing.

OH when I get some disposable income I will be ordering up alot of stuff.

[Patrick Pending]

@kcress:


LEDs are constant current devices - Whoops, I'm pretty sure you didn't mean to say that ;) they are of course quite the opposite.

Cheers,

Pat. Pending

[kcress]

Constant current as in 'you need to supply them with a constant current', NOT a voltage. But I know what you mean. :D