Hello all and thanks for any replies. I have a 55 gallon FOWLR. I have 3 clown, 3 firefish, 1 chromis, 1 foxface, 1 mimic saddler. 2 choc. star and some hermits and nasarius snails. Tank has been up and running for about 6 months after a month and a half cycle period. Levels have been fine until a week ago eveything spike and week off the charts. Did about a 35 to 40 % water change with ready water from store and a week later all levels spiked again. Any one have any ideas what the cause may be. I am also running a marieland c-360 filter. The only think different in tank is that the mimic is killing the snails but i would expect that to be the cause. Also could someone spraying cleaning agents near tank cause these spikes. Thanks again happy holidays to all.