DIY LED Array build

[kcress]

The human eye, which has a truly shockingly huge dynamic range,(10 orders of magnitude!!), trades off for that range by being very poor at seeing changes in brightness.

A 50% change in brightness is required for us to perceive ANY change in brightness. So as you run your lights up or down by eyeball you are actually changing the brightness greatly. I could see where it could be really easy to bleach out some coral by tweaking the brightness a bit.

 

[sphil876p]

Coral colors under LED response....

Coral colors under LED response....

I have noticed this loss of darker pigments as well under the LED array that I have, and did post pics of before and after shots....

I however believe it has more to do with intensity, and not spectrum.
Just my guess or observation, but I had the same problem with the 10k 250 watt metal halide that was lighting my frag tank previous to the LED fixture. The frags are only in about 7" of water with the fixture hanging about 12" from the surface, and only have the LEDs running about 2/3 power. I have an green Acropora in my display tank about 12" below the surface under a 10k 250watt metal halide and it has darker pigmentation than the frag that was in the frag tank. The frag is now pale green and has kept that coloration under the LEDs, but it has continued to encrust its base and grow.....

 

[Reef_Matrix29]

Like I posted earlier I have put my T5's back on the tank for "recovery" of my corals and I see my green brain coral and SPS coming around already. I keep this light on the tank for at least 2 weeks and observe the process. Today I will adjust my LEDs down to 350mA and see if that will be a better fit for the corals. I know that it will not be as "bright" or "intense" as I would have liked, but it may be enough for the corals to thrive and hopefully all colonies survive and not just most.

sphil876p, did that coral that was in your pics that you moved back under MH start to color-up again or is it still pale as it was under the LEDs?

 

[sphil876p]

Like I posted earlier I have put my T5's back on the tank for "recovery" of my corals and I see my green brain coral and SPS coming around already. I keep this light on the tank for at least 2 weeks and observe the process. Today I will adjust my LEDs down to 350mA and see if that will be a better fit for the corals. I know that it will not be as "bright" or "intense" as I would have liked, but it may be enough for the corals to thrive and hopefully all colonies survive and not just most.

sphil876p, did that coral that was in your pics that you moved back under MH start to color-up again or is it still pale as it was under the LEDs?

I moved two pieces, and so far no changes in color though my 250w Double ended bulbs are very bright. I have always had this happen, and attributed it to water chemistry but am starting to realize my lighting might be more to blame. That said, I purchased the piece of montipora on the bottom as a brown 1" x 1" square.......

 

[Canoe]

Does this help anyone explain anything?
Coral Photosynthetic Action Spectrum vs. LED Spectrums

 

[kcress]

Yes it could. What I'm seeing is overwhelming amounts of BLUE on these builds. Chlorphyll A needs red.

Recently I built a very bright wall of LEDs to run a turf scrubber. I used three times the blue verse red. NADA. The algae was not pleased.

I re-made a LED panel with 3X the red verse blue. This worked fine.

 

[james3370]

Yes it could. What I'm seeing is overwhelming amounts of BLUE on these builds. Chlorphyll A needs red.

Recently I built a very bright wall of LEDs to run a turf scrubber. I used three times the blue verse red. NADA. The algae was not pleased.

I re-made a LED panel with 3X the red verse blue. This worked fine.

so for reference on my future build, what would your suggestion be as far as ratio of red:blue:white ?

was primarily thinking doing 1:1 blue:white & doing each independently dimmable to get the color i wanted & then have them all on one master dimmer for overall brightness. i had considered adding a few reds, but was originally advised against it......

 

[der_wille_zur_macht]

I'm dying to find it, but there was a study published in one of the online marine mags related to corals' response to different specific spectra of light. In fact, I believe they used LEDs in the study. The author was trying to tie it into arguments about why diffferent k values of MH bulbs produced different results, and I seem to remember one of the conclusions being that red was somewhat harmful (at least under the conditions in the study, with the species of coral they used, etc.)

Anyone remember the article I'm talking about?

Though I do agree on the whole that there's a lot of blue in the typical LED build. I'm probably going to aim for 2:1 white:blue on my big tank.

 

[james3370]

yeah, i don't remember what thread i posed that question about the reds, but believe the advice against it was cause the red spectrum was considered harmful for the corals....

think the debate on whether adding some UV spectrum LEDs is either good or bad for the coral as well has been discussed but not concluded if i remember correct

 

[der_wille_zur_macht]

I have less biology than electronics, so I'm struggling to understand all this myself. Please don't go on my word alone.

I'd love it if someone with a clear understanding of how corals responded to light would just lay this out for us. I feel like with LEDs, we have a much better ability to build the exact "ideal" spectrum we need/want, vs. T5 or MH, where you're stuck with commercial lamps (that all seem to be a hair wrong.)

 

[Canoe]

well, to confuse it more, in a thread in the advanced section it was explained to me that as long as you had either red or blue, chlorophyll A would grow with either, it didn't need both.

Perhaps if white LEDS - low at the peaks of chlorophyll A - are turned up enough to provide enough energy for the cholorophyll A, the excessive peak in the yellow is causing harm?

I'll try to find the tread. It discussed saturation for coral growth, which I don't understand and have to re-read every time.

 

[Canoe]

I think this is it:
http://www.reefcentral.com/forums/showthread.php?t=1496092

 

[james3370]

I have less biology than electronics, so I'm struggling to understand all this myself. Please don't go on my word alone.

I'd love it if someone with a clear understanding of how corals responded to light would just lay this out for us. I feel like with LEDs, we have a much better ability to build the exact "ideal" spectrum we need/want, vs. T5 or MH, where you're stuck with commercial lamps (that all seem to be a hair wrong.)

i know last year at our frag swap, Sanjay gave an AMAZING presentation on lighting.....just wish i'd paid more attention to the minute specifics when he talked about the different light spectrums & their relation to the coral's needs LOL

maybe ask him his thoughts on just the desired spectrums that we should be shooting for & maybe their ratio/intensity to each other???

 

[g8gxp]

I believe this is the article regarding lighting intensity. There is a lengthy discussion of blue vs. red about halfway down.

http://www.advancedaquarist.com/2009/5/aafeature/view

In addition, in regards to the comment of how corals change multiple colors, this article may provide some insight. It basically talks about how corals can produce varying pigmentation in response to light spectrums.

http://samsreef.com/content/view/22/2/

 

[jonnybravo22]

Please continue discussion above re: coral coloration and LED spectrum. It is quite interesting.

In the meantime -- with regard to retrofitting a spotlight... can someone explain a bit about what if anything is important to consider for the electricals of the original light? Obviously you should make sure you have space and that you can cool the apparatus, but one thing i really liked about Phil's build is that he reused the existing wiring.

Does wiring make a difference as far as needing to match what drivers / power supply you will be rigging it to? I'm looking at a fixture that comes standard with "lamp socket and 110v grounded power cord" (no bulb). Is this compatible with any sized power supply / driver?

 

[kcress]

James et al; As far as I know chroA does need red - see the chart above. It can not "use blue instead". If some coral colonizes A-type it needs some red.

MH provides a broad spectrum that certainly contains some red. Switching to a hopped up blue LED setup could certainly cause some coral to have problems. Just dive in the tropics, everything is not intense blue white.

That said, I suspect you don't need much red. James, I think a few red would be enough, not even enough to necessarily see with the eye looking at a tank.

Color aside I have learned a lot about algae doing a TS and one thing for certain is too much light absolutely causes photo inhibition in algae. As I noted above it could all come down to lights that are just too bright or run too long.

We run turf scrubbers 18 ON 6 OFF. If the setup is too bright decreasing the ON time will quickly turn around the growth and get it happening. We can either run dimmer or run shorter, either way works.

 

[sphil876p]

Please continue discussion above re: coral coloration and LED spectrum. It is quite interesting.

In the meantime -- with regard to retrofitting a spotlight... can someone explain a bit about what if anything is important to consider for the electricals of the original light? Obviously you should make sure you have space and that you can cool the apparatus, but one thing i really liked about Phil's build is that he reused the existing wiring.

Does wiring make a difference as far as needing to match what drivers / power supply you will be rigging it to? I'm looking at a fixture that comes standard with "lamp socket and 110v grounded power cord" (no bulb). Is this compatible with any sized power supply / driver?

I used the existing 110v wire to power the driver, and pulled an additional small gauge wire to power the fan attached to the heatsink. The standard 110v "lamp cord" is huge compared to what is needed, and I only used it for convenience. Whatever gauge is on your fixture should work with whatever driver you decide to use, paying attention to Positive versus Negative on your "wall wart" power supply.

 

[Reef_Matrix29]

I moved two pieces, and so far no changes in color though my 250w Double ended bulbs are very bright. I have always had this happen, and attributed it to water chemistry but am starting to realize my lighting might be more to blame. That said, I purchased the piece of montipora on the bottom as a brown 1" x 1" square.......

Well it looks like the "brown" cap was actually purple, but seems to have grown great under your halides. I have that same Lavendar tip acro in my tank and its doing much better under the T5's than it was the LEDs, but again, I believe that I was hitting them way too much and thought that was why the "body" didn't have color on it like the tips did. Silly me :lolspin:

 

[sphil876p]

Great info on the light spectrum question....
Now I have a weeks worth of article and thread reading homework

 

[der_wille_zur_macht]

I used the existing 110v wire to power the driver, and pulled an additional small gauge wire to power the fan attached to the heatsink. The standard 110v "lamp cord" is huge compared to what is needed, and I only used it for convenience. Whatever gauge is on your fixture should work with whatever driver you decide to use, paying attention to Positive versus Negative on your "wall wart" power supply.

I second this. This is what I've done for my "spotlight" retrofits into desk lamps, as well.