That's just what cycling does - it permits the growth of those bacteria in the filter, but you need SOME ammonia to do this - with fish in the tank, you can only allow a minimum amount in there otherwise the fish are harmed (hence, water changes - this slows down bacterial growth - the less ammonia present, the slower the bacteria grow). Without fish in the tank, you can bring ammonia up to a higher level right away and grow bacteria much faster - no water changes needed during fishless cycling.
Originally Posted by GrannyFlats
46 gal fw tank with black skirt tetras, neon tetras, spotted corys, green corys, 1 guppy, cherry barbs, otoclinus, snails & 4 amano shrimp - plastic & live plants
5 gal QT with green corys & 2 guppies