What causes coral color darkening?

[tiderunner]

I've got a bit of a coral conundrum on my hands. I had this gorgeous lobed brain coral, red and orange with a vibrant green center, and now it's turned a dark, foreboding red all over - just a few speckles of green left. My Acan Enchinata's also changed, its orange and green edges have given way to a dull dark red/brown, with only some color remaining around the mouth area.

The corals are sitting on the sand bed in my 20g H, under 24" Marineland reef capable LEDs, supplemented with ecoxotic stunner strips for a pop of blue and magenta - these are more for aesthetic purposes, not actual lighting. To be honest, I wasn't a fan of the intense white light, so I covered some of it up, thinking maybe the corals were getting overwhelmed. The Marineland LEDs only have four actinic lights, which might be part of the issue. I've actually just ordered some T5HOs to replace them, as I'm not a fan of the LEDs.

On a positive note, both corals are eating Fauna Marin LPS pellets like champs - I was surprised to see the Enchinata take to them so easily. My tank parameters are all stable and within range, so that's not the problem.

I'm wondering, what causes a brightly colored coral to lose its vibrancy? Is it a lack of light, too much light, or something else entirely? Can the colors come back, or is this a permanent change?

[rileyon]

I'm inclined to believe your LED setup was the culprit. Investing in high-quality bulbs with the right spectrum could make a significant difference, but it's uncertain whether the lost colors will fully return.

T5s are often underestimated in terms of their strength, so I'd expect light acclimation to be necessary. Drawing from my own experience with a similar issue in a 10g tank, where a low-powered LED is holding some corals I'm phasing out, I'm fairly confident in this assessment.

[rileyon]

A combination of light intensity, spectrum and photoperiod can impact the symbiotic algae that live on the surface of coral tissue. These algae have pigments that give them their colors, and in lower light conditions, they tend to multiply, making the coral appear darker. I'm no expert, but from what I've read, this seems to be an attempt by the coral to boost food production through photosynthesis.

[dune9x]

Zoozanthellae are definitely present, and with plenty of time and proper lighting, I'm optimistic the colors will return.

[tiderunner]

Thanks for the input, guys. I really appreciate it. Both corals still have some color when the actinics are on, especially the echinata. I was under the impression that those types of corals preferred lower light conditions, but I guess I was wrong.

I've ordered a new lighting setup - Aquaticlife 24" 4lamp T5HO for my 20g H. Hopefully, this will make a positive difference. I've also picked up some ATI bulbs: two Blue+, a Purple Plus, and an aquablue. Fingers crossed it'll help bring back the colors.

[rileyon]

The corals you're referring to do indeed prefer more subdued lighting, but that's when you've got robust lighting in place. Yours, on the other hand, seem to be struggling with inadequate light based on the fixtures you were using. Fingers crossed the new setup will make a difference. T5s are a solid choice, and you've picked some great bulbs, so I'm optimistic about the outcome.

[tiderunner]

Just a quick update - switching from Marineland reef-capable LEDs to Aquaticlife T5HO with ATI bulbs has started to bring some color back to my brain coral. I also rearranged some rocks to give it more open space and light, no more branch hanging over it. The pics are from 12-31-14, 1-11-15, and 1-17-15. I'm really looking forward to seeing it return to its full color. The first pic was under blue lighting, and you can see how dark it was. Color started to show slowly, but wasn't very visible under day lights initially - now, under day lights, the colors are starting to pop out and spread.

[tiderunner]

Just a quick update - it's been 3 months since the last pic, and I'm blown away by how much color has returned. The brain coral's really starting to regain its vibrancy, and I couldn't be happier with the progress.

[rustyfox9]

I ran that light on my 20g H and it's been a solid choice for my LPS corals.