To clean your fish tank filter, let's define the word cleaning. Cleaning usually means soap, water, sterilization. That's not what we're doing here. Our goal is to just free all the waste that's been trapped in the filter and allow the filter to do what its goal is: to filter the impurities in the water by allowing the bacteria that's growing in your biological filter free access to the water. Remember, all the waste, the particulates in the water, is going to clog the pores of your filtration.
So we want to unclog those pores. The best way to do it is to take your biological filter and to squeeze it in water in a bucket from the aquarium. So you'll take water from the aquarium. Stick it in a bucket. Take your biological filter, maybe it's a sponge, maybe it's some bio-balls, and you'll clean it inside the bucket of water until that all that waste is out.
Then you can reuse the filter. Put it back in your filter. Ever year or two years you're going to want to change the biological media because it's just going to start to fall apart.
There's also chemical and mechanical filtration. The chemical filtration would be like carbon. That you'll change every two to four weeks depending on the needs of the aquarium. If the water's getting very yellow then you're going to want to change the carbon more frequently. The mechanical filter would be filter floss, a micron sock, that, depending on the stocking densities and how much you feed, would be changed usually every week, two weeks, three weeks.
But the goal, again, is to always make sure that your filtration system is working properly. You don't want a canister filter to be clogged and the water to be coming out very slowly. You don't want your wet-dry filter to be almost overflowing because the micron socks are clogged.
So, every filter's a little different, but the goal is to not shock your filter. You don't want to take the filter, clean it in your sink, use hot water, use bleach; you don't want to do that. I like to clean the filtration system in water from the aquarium to just remove a lot of the waste and not shock the bacteria. Because, remember, bacteria is what's breaking down the waste in the water, the ammonia, the nitrite, into less toxic forms. So you want to minimize shock.
It's also good to clean your filtration at different times than when you do your water changes. Because when you're doing water changes and gravel siphoning or sand siphoning you're removing a lot of the waste, but you're also shocking the system. So, the less shock you do to the tank the better. Remember, we're trying to maintain a good environment we're not trying to shock it.