Quote:
Originally Posted by ScubaSteve
660 nm makes the corals grow, yes... but... it does so by promoting the growth of zooxantellae, which in turn the coral feeds on. Unfortunately zooxantellae is brown which makes the corals brown out. It's kind of like giving a plant a ton of nitrogen fertilizer: yes, it grows fast but ends up all long and leggy... You get the effect you were looking for but you lose out elsewhere.
If you break out the physics textbook you can figure out how much red light there actually is at a certain depth where you find the corals. You loose a lot of red quite quickly as you go deeper. We are essentially keeping our corals in tide pools compared to their natural habitat, so to get the best behavior out of them you want to simulate the spectrum of light they experience at the depths they naturally reside rather than giving the zooxanthellae what they want (more red).
If you tell me what corals you are experimenting with, I can take a pretty good stab at which zooxanthellae clades are in your corals; from this I could give you pretty much the exact spectrum that clade absorbs (most importantly the absorption peaks). I'd echo the above comment of trying more green than red.
One thing to bare in mind is that all of this will make them grow better but not necessarily look better. You see the coral based on whatever light is not absorbed by the coral (it's own pigmentation + the zooxanthellae) or the light that is re-emitted through florescence. You need to strike a balance between the coral's health and growth and this left over amount to get the best of both worlds.
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It pretty much covers everything for SPS. LPS and softies under the 660nm spectrum does absolutely nothing, they dont lose there color nor do they seem to grow faster.
Ive been testing and playing with PAR38 custom versions for about a year and a half now. What I find is what plants need is NOT what corals, especially SPS needs. Coming from a heavy planted tank before my first sw tank, and reading a ton of hydroponic papers it is evident and tested that blue spectrum make the plants grow short with more nodes of leaves while red makes them shoot upwards with fewer nodes of leaves.
Though corals use the red spectrum it just browns them, from the lighting scheme you described earlier of turning the reds on while you are away and turning them off while you are there definitely wont work 100%. That's just not how corals and there symbiotic algae work. If only that was the case we would all be doing that, the chances are you'll be staring at brown corals even with the reds off.
Ron99 and I have tested with green LEDs a little while we were working on an LED light, and it's quite interesting because the green LED florescent some orange, pink and red corals while the red LED did absolutely nothing in enhancing color.
As for the intensity of the red spectrum, it didnt change the outcome. I couldnt adjust via ramping down the LEDs power, what i did test though was coving up the 1 red emitter 25% at a time, and even at 3/4 covered the corals didnt recover from the brown.
Another thing to keep in mind though milad, the more spectrums you add the more "bands" of color is going to show up in the shimmer. The PAR38 with only RB and CW has white and blue shimmers. The one with the red emitter is tri banded white, blue and red shimmers. and adding in a green made it 4. IMO that makes mixing LEDs a bit weird, since the spectrum is so narrow mixing them + the physics behind refraction of the surface agitation = a tank that looks like a disco ball. haha, its hard to get used to that, as it is hard for some to even get used to the white and blue colored shimmers from RB and CW emitters alone.