I've always wondered what would happen if dead plants and fecal matter lay in chlorinated waters and/or waters treated with strong antibacterials or antibiotics.
I've heard that aquarium tanks owners warn against using strong antibiotics as it can kill nitrifying bacteria which convert toxic ammonia to a safer form of nitrate. Otherwise, ammonia levels can buildup and be toxic to the aquatic life in the tank.
However, that doesn't make sense to me. Even if the nitrifying bacteria die, wouldn't the ammonifying bacteria which produce ammonia in the first place also die? Would there be greater amounts of ammonia in the water after these agents are repeatedly used, or would ammonia levels with nitrate levels together fall significantly?