Today I did a 50% water change and, as usual, treated the tank with a double dose of Prime before refilling the tank. I noticed afterwards that my SeaChem Ammonia Alert showed a positive ammonia level. I double-checked the result with a Mardel ammonia test strip which confirmed the result. The ammonia level is now returning to normal. I am assuming the ammonia spike is due to mulm at the bottom of the tank being stirred up during the water change (although I do my best not to stir things up too much). I do not want to expose my fish to any appreciable ammonia levels. Is there a trick to keeping this from happening? How hazardous is this to my fish? Since my plants are doing so much better (i.e., not rotting away), there's not much stuff to vacuum up. Any ideas appreciated.