Several days ago, I did a 100% water change on my 20 gal QT because of an untreatable bacterial bloom. It has been running fishless for 2 months without any chelated copper. I have a lot of ceramic biospheres in there from my sump, as well as a sponge and mineral media in my Seachem Tidal 35 HOB filter. Yesterday morning, I got a Melenarus wrasse and and golden head sleeper goby. Ammonia was 0 in my tank when I added them. However, I checked the total ammonia today and it was 0.4. Seachem alert badge shows 0 toxic ammonia. Wrasse appears to be absolutely fine, but the goby has been breathing very rapidly since this afternoon. I dosed Prime this afternoon to reduce the ammonia levels, and I'm currently preping saltwater for a 25% water change. I also put a small airstone in to help the goby. I have no idea how the ammonia spiked so fast. My only guess is that I am experiencing a mini cycle because I deplenished a lot of nitrifying bacteria when I replaced all the water in the tank. Any advice would be appreciated.