I have a 55 gallon tank with a Marineland Bio-wheel 350 and a sponge filter. The tank has been running for about 4 months now. We have 5 giant danios, 4 blue rams, 5 guppies, 4 tetra serpaes, 5 neon tetras, 1 blue gourami, 1 dwarf gourami, 1 cory cat, and 1 pleco. My problem is ammonia I can't keep it under control. I found a filter that said it scrubbed ammonia out but it doesn't seem to be working. Can someone suggest something to help? What can I do to fix the problem.?