Originally Posted by ChuckinMA
Hello - rinsing your filter media in tap water is not a good idea since it can kill off your good bacteria. You have the benefit of non chlorinated water, but still I'd recommend using aquarium water to rinse out the filter media.
Not true. Even chlorinated water rinsing will not kill the nitrifying organisms, they are far more hardy than commonly thought. It would take a much higher concentration of chlorine than is in tap water to do much to them.
Having said that, if you want to rinse in old tank water, that certainly wont hurt.