Sponge Filter Q's

[mobyfish]

Hi all, I'm setting up a 150 gallon Folwr and I've been cycling my rock in a plastic trash can for 2-3 months now. Today, I went to my local fish store and got a sponge filter to use for my quarantine tank. I was always under the impression that you had to cycle this filter just like any other method of filtration but the guy at the store said theres no reason to cycle because I' supposed to clean it often anyway. He said to just do big water changes weekly and quarantine the fish that way. Anyway, I was wondering if this was true and whether or not you are supposed to seed a sponge filter or just do big water changes weekly when quarantining fish. Also, since I do not have my main tank up and running yet I cannot just seed my sponge filter in there. So how should I go about doing that? As you all can tell I have never used a sponge filter before. Thanks!
-Matt

[Gatorfan]

It will probably depend on the medications you use. If it's just for observation, a seeded filter will make it easier. Some medications can wipe out bacterial populations making water changes the only option.