I'll add my $.02. I also have a goni and for a while it looked like it was on its way out. It looked great in the store but over time started getting smaller and smaller. I started feeding Oyster Feast, which may or may not have stopped it from continuing to waste away but it definitely did not look great. Based on an old paper I found written by Julian Sprung and advice from my LFS as well as a talk from last year's Macna that mentioned gonis needing Manganese, I switched from Reef Crystals to Tropic Marin. That seems to have really brought mine back from the brink. The polyps are getting long and fat and it is starting to reclaim some of the territory it lost. Also, the Tropic Marin seems to be a better salt overall than Reef Crystals. Not sure if that's what you use, but there is none of the residue in the bottom of the bucket when I mix it up. I was also trying 2 Little Fishes Iron supplement before switching salt because it contains manganese but it didn't seem to help much. Plus I was told that algae loves iron and I certainly was not testing my tank for iron. In my case I didn't know much about goniopora before I bought mine, but the LFS said "it will be fine" and I foolishly believed him without doing my research. Once it started to deteriorate and I did some reading I almost wrote it off, but fortunately I seem to have found a solution that worked for me. Good luck!
