These LED's just aren't cutting it. Or - are they?

[waynemah]

16" tall water column with 9" between water and light gives you 25" to the sand bed. I ran my lights 15" above my 24" tall tank with great success (39" above sand bed). If you raise the light up a bit, you can continue with your current brightness and get better coverage. I would likely start by raising it about 5".

If you decide to turn the lights down a bit, I would say cut all colors equally. Your LED lit tank will look about 30% duller than your T5 tank. Every time I look at my tank now (with T5) it's like a glowing kick in the face compared to what it was with LED.

[Slyguy00]

Originally Posted by waynemah

I ran my lights 15" above my 24" tall tank with great success (39" above sand bed).

Was that at 100%? 39" seems really high.

[waynemah]

Originally Posted by Slyguy00

Was that at 100%?

Those had 80 degree frosted optics and were run at 80% on the white and 100% on the blue. Having no optics will make our heights different, but raising the fixture itself is a tool to improve coverage and lower the brightness at the same time. If your coverage is good, drop the brightness.

[Slyguy00]

Is there an average height people run their lights above the sand bed? I just hung my maxspect razor yesterday and am not sure if I should keep it at the same height as the legs (like 8") or move it up more.

[The Guy]

Originally Posted by Slyguy00

Is there an average height people run their lights above the sand bed? I just hung my maxspect razor yesterday and am not sure if I should keep it at the same height as the legs (like 8") or move it up more.

I have my AI's 12" above the water line I ramp up to max. on blues & royal blues @ 80% with whites @ 60% starting 3 pm to 4:30 pm what I call mid day sun. Then ramp down from there. Had to play with them to get to a sunrise to sunset that gave me the best over all light for the corals, I probably could treak more but this seems to work for me so far.

[Ron99]

I think there are so many misconceptions around LEDs even after several years of use and a more mainstream acceptance. You could happily grow corals under nothing but white LEDs. The coral would get enough light for photosynthesis and grow but the colours would not look pleasing to our eyes. You could also probably grow corals under nothing but blue LEDs but, again, the colour would likely not be what we want for our own enjoyment.

All the other colours of LEDs being added to fixtures; green, red, violet; are not necessary for growth or coral health but are useful to fine tune the "look" of the corals for us.

As for the topic of this thread, bleaching does indicate too much light. Blue is high in PAR in the spectrum that corals utilize so turning them down or raising your fixture will help. And you need to give the corals time to acclimate to the new light intensity. They won't change overnight.

IME, it's better to start LEDs higher or at lower power and have your corals start to brown a bit, then turn them up or lower them than it is to shock them with too much light and bleach and potentially kill them.

[Jakegr]

Originally Posted by Ron99

As for the topic of this thread, bleaching does indicate too much light. Blue is high in PAR in the spectrum that corals utilize so turning them down or raising your fixture will help. And you need to give the corals time to acclimate to the new light intensity. They won't change overnight. .

Just a note - blue light is not higher in PAR than red light. PAR is measured as umol photons 400-700 nm / m^2 / s. The PAR from 20 photons of blue light is equal to 20 photons of red light. I think you mean blue photons contain more energy than red photons, which is completely true. This is a bit of weakness when relying on PAR as your sole indication of light quality... it values all photons between 400-700 nm equally.

Also, re: growing photosynthetic organisms under monochromatic light - there are usually a lot of problems with that as blue light, red light, and far red light play many non-photosynthetic physiological roles. You are completely right about growing corals under white LEDs only as that is not monochromatic light. Growing them under only blue or only red probably is not a good idea for the health of the coral.

Also, the PAR meters used by hobbyists miss blue photons and tend to underestimate PAR in fixtures with a lot of blue light.

I think a lot of misconceptions about LED lighting are due to hobbyists having misconceptions about the nature of light and its measurement.

[neoh]

Originally Posted by waynemah

16" tall water column with 9" between water and light gives you 25" to the sand bed. I ran my lights 15" above my 24" tall tank with great success (39" above sand bed). If you raise the light up a bit, you can continue with your current brightness and get better coverage. I would likely start by raising it about 5".

If you decide to turn the lights down a bit, I would say cut all colors equally. Your LED lit tank will look about 30% duller than your T5 tank. Every time I look at my tank now (with T5) it's like a glowing kick in the face compared to what it was with LED.

I did indeed turn them all down equally. Well, except the white since it's only at 6% anyways.

The lights are definitely duller than when I ran T5's.

I'll try turning the light down as opposed to moving the lights up, as it would illuminate the room a little too much. I'll give it two weeks - if nothing happens, I'll move them up as recommend.

I appreciate everyone's input! And monocus, I'll need to finally put you up on that offer for the PAR meter.

[waynemah]

Originally Posted by neoh

I did indeed turn them all down equally. Well, except the white since it's only at 6% anyways.

The lights are definitely duller than when I ran T5's.

I'll try turning the light down as opposed to moving the lights up, as it would illuminate the room a little too much. I'll give it two weeks - if nothing happens, I'll move them up as recommend.

I appreciate everyone's input! And monocus, I'll need to finally put you up on that offer for the PAR meter.

6% seems quite low! But then again every light is different. Do you have any pictures with white balance to portray the look of the tank? It might be a case of not enough light. Par meter at this point could go a long way!

[neoh]

Originally Posted by waynemah

6% seems quite low! But then again every light is different. Do you have any pictures with white balance to portray the look of the tank? It might be a case of not enough light. Par meter at this point could go a long way!

Certainly couldn't hurt.

May be low, but the whites don't really make the colors pop as well as I like. I've got a lot of green coral.

As far as I know, whites don't do much for coral growth, hence why I've cut them out.