Hi, this is my first post on R2R. I've been using this forum as a resource, just reading threads, for almost a year now, and it's been fantastic, so when I encountered this problem I couldn't figure out how to solve, I figured I'd join. (But I'm sure I'll use this forum for a bunch else now too!) But now, down to business. I have several small zoa frags in my aquarium, and one small colony. After looking great for a while and growing, my zoas suddenly all closed up for well over a week, and my colony started to actually melt. All my other corals (just mushrooms and a neon sinularia leather) were totally fine. I tested the water again and again and nothing changed rapidly or was too far from where it needed to be, so I decided the initial cause of the melting was not a water quality issue. I checked at night after the tank was in total darkness for a few hours with a red flashlight and could not find any pests. I repeated that for several nights. The only obvious issue was several small aiptasia that had sprung up near the colony. One managed to get right into the middle, and my hypothesis now for the melting (as it happened from the inside of the colony out) is that a minor injury/stress due to the aiptasia stinging the zoa was further bothered by me using Aiptasia-X quite liberally very close to the colony, leading to a bacterial infection or illness of some kind. At the time of this happening, I was very stressed already by other things and so when my zoas nose-dived for seemingly no-reason, I sort of gave up for a week or so instead of actually attempting to fix things. Fast forward a couple weeks and all the zoas in the tank have reopened, including what's left of the colony. I've been attempting to help them recover by spot-feeding them reef roids once a week and essentially just tightening up on my maintenance. I am noticing improvement, but I can't seem to get to the real root of the problem. All my zoanthids are opening, but they all seem to be irritated by something; they aren't opening fully all the time, some are remaining only partially opened throughout the day. When they are fully open, the skirts themselves look completely fine. The base of the zoas however have become slightly transparent in places, and have ceased spreading (no new growth whatsoever). The bases/stalks also seem to have gotten thinner, sort of 'pinching' in at some spots. They even look to have receded a bit in places, on all the frags, not just the colony. All my other corals are showing decent growth. Sorry for such a lengthy post, but I'm trying to provide as much background as possible, because I'm really stumped as to why my zoas aren't doing well. Hours of research that usually give me clear answers has told me little to nothing, except that it could be a variety of issues. With that in mind, I'm going to make this post even longer: Here is some info about my system, as I know that's important. System is 56 gallons (37 gallon display). Red Sea Max E 170, with in cabinet sump upgrade. Reef octopus 150 space-saving protein skimmer. (Skimmer is overkill on this size tank I'm sure, but I intend on increasing bioload with more fish/inverts and feeding corals much more regularly sometime in the near future) Light bioload: neon goby, firefish, yellow watchman goby, some snails and a hermit crab. System has been set up for about 10 months now, addition of in-cabinet sump and reef octopus protein skimmer happened just after Christmas, so that part is very recent. The issues with the zoas started probably in early Novemeber, for reference. Nitrate is 0-5, Ammonia/Nitrite are 0, salinity (specific gravity) is 1.027. Temp is consistently 78-79. KH is a bit high at the moment at 12 (it is stable at 12, though), this is due to me not having been dosing calcium much recently, and my top-off water being tap, not RO, which has a relatively high KH. (I know tap isn't ideal, but I've thoroughly tested my water and I don't think its use would cause an issue as pronounced as this.) Calcium is around 330, I'm working on slowly raising it. Light is an AI Hydra 26 LED. 14K, 42% intensity as the tank is just softies. I can't tell if the issue I'm having is related to too much light or not enough. I would really appreciate some help trying to figure out what's wrong... I'm stumped. Sorry the post got so long, I've never used a forum and will have to work on my shorthand haha. I've included a pic which is pretty terrible but I can't get much better, it is of the colony that melted. The rock you can see in the middle of the remaining zoas went from covered to bare in a few days. Eagle eye zoa frag also in the pic has a few polyps not opening, an example of the issue I'm having with all of them.