I do not have animals in a cycling tank. It was done cycling more then a week before I put in the inverts, those I drip acclaimated for 3 hrs. I didn't drip acclaimate the fish because I didn't want them in the water they were in for to long, besides, I always acclaimated fish this way, and never lost one before. My kids gave the cromis to me for mothers day, one fish per kid. They were so excited to be giving me my first 3 fish! I know it was alittlle soon after cycle ended, but they were damsels so hubby thought they would survive, I still don't think it was a question of my tank killing them, they came from some nasty LFS and may not have lived to long there. My ammonia level was so slightly high, am not even sure it was high at all, all other levels were within normal range. I am not a beginner to salt water fish, just been out of the hobby for several yrs and need refreshing in some areas. I do remember a diatom outbreak in my 6 salt tanks I use to have, but that was when I used tap water.