Too much light for GSP?

[AndyR83]

I’ve noticed that my GSP lost most of its color over the past week or two. The tips of each polyp are green but the rest is white. I’m wondering if this is due to excessive lighting perhaps? Should I raise the light up more?

Most of my tanks are FOWLR, and this one has only a couple of ‘easy’ frags. I’ve got a decent amount of “book” knowledge about coral care but almost no actual hands on experience keeping them.

The light is an AI Prime 16HD. I positioned it a bit closer to the surface of the water than may be normally seen because of how deep the corals are. The light is about 4” above the water and the GSP is 16” below the surface.

The frag is about 6 weeks old. It took a week or two to open up initially but was green and looked good until about a week ago. It has looked like this since then.

Today’s parameters:
Temp 75.4F
SG 1.024
Ammonia 0
Nitrate 40
dKH 9.1

I need to purchase reagent for my Phosphate checker. When last checked, it was 0.08 (three weeks ago.)

 

[Ron Reefman]

Two comments and a question:

The corals in the first 2 photos don't look at all like GSP to me.
75F is a bit on the cool side for corals. Not terrible, just lower than most reef tanks.
Is that a live sea horse in our tank?