i've used Nitra-Zorb which removes ammonia/nitrite/nitrate before (at my fiance's parents house on their fish) and it works great. Its rechargeable too, which is nice. Granted, its better not to have ammonia/nitrite/nitrate in elevated amounts, but when things get out of hand, it helps to have something to combat the problem. I haven't done it, and I don't know if it is a good idea or not, but this stuff says it lasts 3-6 months and that you can leave it in the tank all the time, to help act as a "buffer" for any spikes that may occur, for various reasons.