I have a 55 gallon tank, which has been set up for a little over 2 months, and the ammonia levels are just as high now as they were 3 days after I got the filter for it. I had some baby sailfin mollies in it, who, up until last nite, were doing fine. They began breathing heavily and looked terrible so I moved them to another tank, where they seem to be ok now. I'm not brand spanking new to aquariums, I have an established 45 gallon, which has been set up for nearly a year now, and I've had little to no trouble with it. The nitrates occasionally get high, but that is fixed easily enough by vacuuming the gravel and cleaning the filter. The fish in there are thriving, a couple angelfish even breeding. About a month into what I thought was the cycle of the 55 gallon, I added some Amquel+ to the tank, since ammonia levels were still very high. It clearly states on the bottle that it will not interfere with the cycling process, and everything I've read online about it claims the same thing. After 9 weeks or so into letting the tank run, nearly daily water changes, usually about 20%, once a 50%, feeding only every other day, removing half the fish, so that there are only 4 small fish in it now, and the ammonia STILL hasn't gone down. My 45 took about a month to cycle, and as I stated above, I've had very little trouble with it, but the 55 is rapidly becoming the bane of my existence. Could it be the difference in filters? On the 45 I have a Rena Filstar canister filter for a 75 gallon tank. The 55 has a Penguin 350 Bio-Wheel, which claims to be for tanks up to 70 gallons. The guy at the fish store said the filter has nothing to do with it. If this is true, the only other thing I can blame it the Amquel+, since it's the only thing I did differently from the 45. Any advice, tips, and whatnot would be appreciated, as I'm about 2 days away from taking all the water out and maybe adding a hamster or something.