Early signs of browning in acan corals

[wiredonfish]

I'm pretty sure I'm on the right track here, but I thought I'd run this by you all. I just added a new Acan lord to my 29g tank, and it's sitting on the sandbed under an Aquamana COB LED that's about 18" off the water. My current settings are 15% white and 30% blue. I've been using an eggcrate cover from Home Depot, which I know reflects a lot of light.

Today, I took the eggcrate top off for a bit during feeding, and I noticed the color in the normally purple area of the acan had shifted to a brownish hue. I put the top back on, and a couple of hours later, the acan was back to normal.

So, here's what I'm thinking:

1. The eggcrate top must have been reducing and dispersing the intensity of the LED's, and when I removed it, the lighting changed, which didn't agree with the acan.

And

2. Indirect lighting might be the way to go. I've got a spot in mind just south of a frogspawn, at the base of the rock, which seems to get most of its light reflected back from the sand and the nearby corals.

Does this sound reasonable to you all?

[sweetie_22]

IME, I've never seen color shifts occur that quickly. In my experience, browning is usually a sign the coral's not getting enough light. I've always had better luck with my corals when they're in direct light.

[felinxo]

Another possibility is excessive zooxanthellae within the coral, which can be linked to high nutrient levels.