I have a ten gallon tank that i set up a week and a half ago. I let it run for three days, tested water, and added fish(2 platies, 2 bloodfin tetras, chinese algae eater, bamboo shrimp, and a neon blue dwarf gourami). I will be switching from a tetra whisper filter to an aquaclear.
use some of the older filter medium to seed your new filter and you will be fine
[phpzon]Fish Bamboo Water, 30, HomeGarden[/phpzon]