I have been feeding my tank with liquidlife bio- and coral-plankton and occasional marineplankton (with cyclopeeze). It is in my 24g aquapod with PC lighting (64 watts), and it sits about halfway down my water column, ~8-10 inches from the light (6-8 inches under water). Lighting schedule is actinics on at 0830, daylights on at 1000, daylights off at 2100, actinics off at 2130. Lunar lights on 2130 to 0830.
Water flow is mild to moderate, the stock ~290g/h pump with hydor rotating head on the output. I am thinking of adding another power head to the tank, but have yet to do that.
I had a small nitrate spike recently which I have been bringing down with 5g water changes (not as quickly as I would like, but I am getting there and none of my other corals or fish look stressed). I thought the spike was from overfeeding, so I have cut back on the feeding, and had not added any plankton for 5 days. My fish still got a few mysis every other day. This coral was looking good until today, when only ~12 polyps were slightly extended. All the polyps looked "closed", rather that the "skeleton" appearance that it gets when they retract (like whenever it gets handled).
I tested my water tonight and found that my nitrates are down, but so is my pH, to ~7.8. I did another water change tonight. My freshly made saltwater tests at a perfect 8.2. I am thinking of dosing with small amounts of baking soda to try to get the pH back to 8.2.
The only other thing is that I found my hammer coral knocked down in the tank last night. Don't know how it got dislodged, but it was upside down in my rock, ~6inches below where it normally sits and about 8 inches away from this coral. When I righted it, it was covered in slime, and I don't know if it released some sort of toxin into the water that is irritating this one. If so, I figure the water change will help. Hopefully my carbon will too.
I bought this coral cheap, because it had been pretty stressed in transit and at my LFS, with the underside (which you can't see in the picture) being completely dead, probably from lying in a sandbed. I thought it had been doing well in my tank, with the polyps extending nicely over time.
Right now I am left making small adjustments, and hoping for the best.