Low Light levels inducing better coloration

[FlyPenFly]

Was just browsing through Dana Riddle's newest article on Advanced Aquarist and ran into this bit. How many people have noticed that lowering light levels led to better coloration?

I think for certain species of acros like red dragons and tricolor valadias, lower in the tank positions have led to better coloration. That's been my direct experience with a tricolor in my 8 bulb T5 setup. It was almost bleached white in many places about 65%. When I moved the colony to the edge of the tank receiving not too much light but still getting full coverage, it colored back up in a rich deep blue purple color in about 3 weeks all the areas that it was white.

http://www.advancedaquarist.com/2013/12/lighting

There are intriguing reports of hobbyists and commercial coral farms growing brilliantly colored corals under extremely low light levels. At present, the hypothesis is that the relatively high amount of blue light at relatively low light intensity (PAR) is the environmental trigger for not only rapid growth but extreme coloration as well. This flies in the face of opinions of many hobbyists, where the thought is that corals, or more correctly, their zooxanthellae, are infinitely adaptable to higher amounts of PAR (the 'more is better' train of thought). Experiments are planned to examine photosynthetic efficiencies of LEDs producing differently colored light. In addition, I have new information about blue light and its fate when promoting photosynthesis (or not) in corals' zooxanthellae. But that is a discussion for another time.

Researchers have, in the last ten years or so, determined the wavelengths needed to induce coloration in corals. We can quantify the amount of light per wavelength or bandwidths and determine the suitability of a particular light source in promoting these colors.

While I have put a great deal of time and effort in writing this article, and consolidated data I have collected on natural reefs in Hawaii over the last 14 years, the information presented here is but a foundation for further research.

 

[asylumdown]

That is very, very interesting, especially the striking difference in the colour of tank water vs. reef water. I've not used activated carbon on my current tank, but that alone is a strong reason to do it every so often.

It makes me wonder if triggering more intense coral coloration would simply be a matter of reducing the amount of white and red a fixture like a radion would put out, or if you'd need to actually increase the number of blue diodes.

It also gives me something to think about regarding the serious bleaching I've experienced with certain species of LPS under radions that hit a max intensity of 75% with all channels at 100%, but that completely recover to their original lustrous deep colours under something like a Kessil A150 Ocean blue, which has no red or green, and much heavier weighting towards blue.

 

[Nano sapiens]

My understanding of this topic is that corals can produce a variety of fluorescent and non-fluorescent pigments depending on the spectrum and intensity of the light source. There are minimum intensities, however, where a particular pigment is weakly expressed (or can't be produced at all), but the coral can still grow and be healthy.

Coral growers can provide relatively large amounts of just the correct wavelengths to trigger the desired coloration. This results in lower PAR since a full spectrum type lighting is not used (no 'unnecessary' wavelengths that would increase PAR) and therefore they can decrease energy usage. When the corals are conditioned this way and photographed under the right lighting they can look absolutely 'mahvelous'. The flip side is once the corals are in the hobbyist's tank all bets are off color wise unless the same type and intensity of lighting is used, nutrient levels and flow are similar, etc.

'Full spectrum' lighting can help our eyes to see coloration that would otherwise be weakly visible. Providing tried and true ratios of various blues and whites and then adding just enough of the 'missing colors' to optimally render coral/tank coloration has been recommended and generally won't result in super high PAR values being necessary. I used this technique with my LED array and 130 PAR (sand bed) - 250 PAR (mid depth) is sufficient to nicely color up a wide variety of corals (SPS, LPS, Rics, Zoas) with 8 hours/day.

 

[Timfish]

Coloration in corals is an incredibly fascinating and complex subject. Dana Riddles comment "While I have put a great deal of time and effort in writing this article, and consolidated data I have collected on natural reefs in Hawaii over the last 14 years, the information presented here is but a foundation for further research." says quite a bit about just how complex! Reading some of Riddle's other papers there are dozens and dozens of flourescing and chromo proteins which are utilized by corals for different intensities and spectra. Throw into the mix the various symbodinium spp dinoflagellates which provide degrees of brown to golden yellow coloration depending on population density and it's safe to say we will be learning things for a long, long time.

 

[MrIcky]

It also gives me something to think about regarding the serious bleaching I've experienced with certain species of LPS under radions that hit a max intensity of 75% with all channels at 100%, but that completely recover to their original lustrous deep colours under something like a Kessil A150 Ocean blue, which has no red or green, and much heavier weighting towards blue.

I've had an almost identical experience. I wonder if the constant advertising and pushing for high par especially in LED systems has been bad for the hobby.

 

[Nano sapiens]

I've had an almost identical experience. I wonder if the constant advertising and pushing for high par especially in LED systems has been bad for the hobby.

It is becoming apparent that it has...

I found this rather lengthy article recently which does a nice job of providing an explanation for the problems many have faced when using high-powered of LED lighting (click on the PDF link for the article + photos):

http://www.reef-eden.net/Corals-Conifers And LED-A New Perspective.htm

 

[SPotter]

Im so happy to see this article. I used to have an extremely powerful led light with t5's and had the hardest time with sps. A friend of mine was using 2x400w mh's on his 6ft tank and was having issues with his sps. After many discussions about about running higher par for shorter periods of time or lower par for longer periods of time he decided to switch out 3 x 250w mh's with the same photoperiod as with the 400's and the cloration and growth he is experiencing in his tank is amazing.

 

[jbraslins]

I like this part of the article. It kind of shows what I was thinking about lateral PAR spikes under most LED fixtures.

Seems like LED makers should focus on making light more even laterally, PAR and spectrum wise.

Wider optics, more diffuse light, and more variance/movement across the fixture for better sun movement across the sky simulation.

Fixed Intensity drift over short distances 'A consideration'.
We commonly look at intensity drop over vertical distances as a means of gauging ‘punch’ or depth penetration. Rarely do we look at what is happening over a lateral plane to that light intensity however. One of the key things noticed during these tests were the marked differences in changing intensity over relatively short lateral distances. This ranged from just 100 µmol photons·m²·s over 15” (6.6 µmol photons·m²·s / inch) in the case of the 3 Teszla’s, to a whopping 150-200 µmol photons·m²·s / inch on occasion for the more focused Brand-B units. This effectively means that if we were to place a 10” diameter coral under these two lights, at 6” under the surface, one would have an intensity variance of just 66 µmol photons·m²·s across its 10” span, whilst the other could receive a variance of anything up to 826 µmol photons·m²·s across its 10” of surface area. This is in stark contrast to the wild model, where most un- shaded corals generally receive a balanced amount of ‘incoming’ light across their entire surfaces as an average, and then use their structure, pigments and the angle of incidence to alter that intensity to within acceptable ranges. Although surface motion does cause rapid variations in intensity which we commonly call 'glitter lines' , these areas of high and low intensity are permanently moving, sweeping across the coral on a constant rapid basis, whilst the 'average' reading taken over a period of time will be the same across the entire coral. This is very different to having a permanent high degree of variance in place across a given coral. This may be something worth considering as corals grow out under such conditions, or in situations where we are looking at placing a new coral within the direct light path.

 

[GroktheCube]

It is becoming apparent that it has...

I found this rather lengthy article recently which does a nice job of providing an explanation for the problems many have faced when using high-powered of LED lighting (click on the PDF link for the article + photos):

http://www.reef-eden.net/Corals-Conifers And LED-A New Perspective.htm

Very interesting article!

A few of my corals, especially those in higher light areas, are definitely suffering from "colorful top pale bottom syndrome". I think my stylophora is the worst.

I may try elevating both my T5s and LEDs a few more inches to see what happens.

 

[t4zalews]

I feel that lighting power and tank nutrients need to be at a balance for good coloration. If you run a tank with a lot of PAR, the corals need nutrients and food to handle the extra energy that they are given. If running a low nutrient system, the corals will let go of their zoox and bleach because they cant handle the high amount of energy they are given.

The evolution of today's reflectors are also much more efficient at putting light down into the tank, so the need for strong bulbs are not needed as less light penetration is being wasted. I couldn't move my lights up any higher, so I went a wattage lower from 250w to 175w and everything responded better.

 

[FlyPenFly]

Yes, I do think there is an equation out there and it's probably unique for each specific morph and variant of coral let alone different species.

Light Energy, Flow, DOC Nutrient Availability, Light Spectrum, Zooplankton and Phytoplankton