Can anyone help with this. I have bought a couple of zoa’s that I really liked, the first was a single stalk and was doing great for a week then started closing up until it stopped opening then died and disappeared. I then got a frag of 6 stalks and exactly the same is happening to them. I have got 2 sets of dull ones that I don’t like too much and they are thriving and all my other corals are thriving (except the torch). Water parameters are good.