When do I replace the filter?

cleaning and changine

I clean my filter each week during water changes, just swish it in old tank water. I replace it when I start to notice stuff floating even after cleaning the filter cartridge and tubes and housing of the filter. If you have biowheels, don't worry about disturbing the bacteria, most will be on the biowheel and you won't disturb that very often, but do swish it in old tank water to clean brown bio-slime that may be so thick that it falls off into tank.

So, feel free to clean or replace the cartridges as needed, and leave the biowheel alone as much as possible, if you do need to clean it, be careful to do it correctly.

eventually youll have to
clean the filter i try to do
this when im changing the
water, which is once a week
or sometimes once every
other week ...

Just swish your filter paddings around in old tank water once in awhile to clean the gunk off them. I do mine maybe monthly or so. I also swish my biowheels in old tank water once in awhile, they get algae and stuff growing on them sometimes that can gunk them up and make them not turn as well. Just depends. I have some tanks that the biowheels never seem to get dirty and others that get gunked up pretty fast.

I don't actually change my filter paddings until they are starting to fall apart. If you have two sets of filters, you can change them one at a time a few weeks apart to keep from disrupting things too much. Doesn't matter as much with a biowheel since most of the bacteria will be on there anyway.

I have an emperor 400 that has 2 places for media. I just have the sponge filters in both of them. That way I can clean the front filter, and move the back filter to the front so I'm sure to always have bacteria in my filter.