Fishin for ideas here... I have a purple/pink stylophora (that's what the previous owner said it was) that isn't looking so hot anymore. It has grown like wildfire over the past year - probably a 2" frag to several large fingers, see below. This is a pic from when it was doing well: Recently I have been doing a lot more to the tank. Several heavy water changes, trying to get my alk back up (from 5-6ish to ~10, slowly), took out an ineffective Tunze9002 which was never running, and generally been tinkering a lot. The rest of my numbers seem ok. Phosphates and Nitrates aren't measureable (Whatever is in there is getting eaten by macro or nuisance algae, I assume. Ca is at 480, Mag at 1550. The only thing that I measure which is off is my alkalinity, but it was low for a loong time - basically when all this growth happened. Anyway recently it's begun to slowly lose some color and I'm getting almost no polyp extension. Most of the polyps near the mid to bottom of the coral are retracted, like a few of them in the picture above. No tissue death yet, fortunately, but I am really hoping to avert disaster here. I recently added a few more corals but nothing that I know of that has any sort of allelopathic activity; a pectinia coral, a blue acro, a small chalice. The last change is that I added a cherub angel to the tank. I haven't seen it pick at any coral at all, and he sleeps at night, but it could be that he's bothering it. I just have no real evidence of him nipping, and I figure he'd hit the LPS first anyway. Does anyone have any recommendations on what I should check, or what might be causing this? I'll try to get a pic when the lights are on again so you can see the difference.