You don't need to rinse your filter until it starts backflowing. This is when water starts coming out around the intake tube rather than out through the outlets. Just gently swish it in tank water and put it back in. If you have a carbon filter that needs to be changed/refilled but I'm not sure how frequently. I have carbon filters but I don't use them unless I am removing medication, setting up a new tank, or something has spilled in the tank. Normal filter media doesn't really need to be replaced unless it is basically falling apart IMHO. The people who say change it every four weeks and so forth are probably trying to sell more media or may be talking about carbon. BTW you can refill a carbon filter bag with activated carbon which can be purchased at your LFS. This will probably come out cheaper than buying new filter bags.