So, I've been doing 50% water changes on the tanks. Both of them have had 8 ppm in ammonium and dark purple on nitrites while the nitrates stayed between 10-20 ppm. The ammonium would go down to 2 ppm afterwards and the nitrites to a lighter purple. All the water I took out, I used API water conditioner, aquarium salt, and ammo lock since our tap water does have some ammonia in it. Tonight, I walked past the tanks and the120g was clouded white and my fish were all at the surface trying to breath and some not moving at the bottom of the tank. I quickly drained the tank and moved the fish into a large plastic container with aerators,and new water which tested at .5 ammonia, 0 nitrite, and 0nitrates. So I know they'll be good for a while. I'm thinking the problem is the fluval fx5. I don't think it's working right. It kicks on but hardly blows any water out and the intake doesn't seem to have too much suction. I'm going to clean this monster thoroughly tomorrow after work and buying a new fluval. Do you think from the previous threads this could have messed up my cycle and wiped everything out of this 120g tank? Any suggestions on what I can use as cleaners for the tank walls? Also, there was a horrible swampy gas smell in the water. Could that be an indication of disease or infection? Thanks.