Hi everyone I'm new here and to sw., I've had freshwater for a few years. anyway I started a fowlr tank at the start of march.It's 55gal. live sand live rock some of the rock was not "live" hang on protein skimmer and hang on fuge with chaetomorpha. last week I added a banner fish and a bangai cardinal. today the banner would not eat and started breathing fast and ended up dying. I tested the water and there was some amonia after getting a 0 reading last week. could it be because some of the rock was not live and it could be cycling still? I almost wanted to give up on saltwater but I'm hoping to figure it out.