lot of good info there^ If you are worried about your water I would do a water change too like was mentioned. After that when zoas aren't looking their best I dip them in coral revive or coral RX. Dipping them helps disinfect wounds that may have developed in the handling process. Lets face it, we slosh our corals around in a bag from the LFS, and they get some rough handling. Sometimes it can cause tissue damage, and that tissue becomes infected. Cleaning it will help keep infections in check, and it is a good practice to dip corals in this way I feel no matter how trusted the source b/c they type of injuries happen. Try that with the zoas now, you will be surprised what a dip a day for 3 days in a row will do for struggling zoas.