How often should you clean a cannister filter?

Even when you have a top cannister filter, it will require regular cleaning. These are essential actions to ensuring longevity of the filter and the fish. You need to know how and when to clean the filter though!

Cleaning your canister filter:

This youtube tutorial is a great start for your cleaning:

Filters should be cleaned out about every 2 – 3 months and a water change should be done every month. I prefer to clean them both out at the same time as it makes it a lot easier. Some people don’t clean the whole filter out at once though.

Important note on cleaning and the nitrogen cycle:

The filter works because of something called the nitrogen cycle, and that uses good bacteria inside the filter to turn waste products into nitrogen, release as gas through the surface of the water. So when you clean your filter out, you must make sure that you use treated water and not water from the tap!

The mechanical canister filter cleaning

You should focus on cleaning only the sponge pad or the fine filter pads. We call that the mechanical filtration. Remember again to only use the water from the tank or treated water to clean it. Most canister filters follow the same format of a 3 stage filtration process like so:


These mechanical filters and simply crude filters designed to pick out particles of dirt from the water, they can harvest a lot of bacteria, but that gets washed away when you clean them. That’s why the biological filters are so important. These very rarely need replacing because they are just a sponge basically.

Also note the biological filtration methods. This keeps good bacteria in the filter to clean and aid the nitrogen cycle.

Chemical cleaners

Chemical filters are filters like carbon filters. They are not intended to clean out bits of dirt from the tank, but improve odor of water color and stuff like that. It cleans a lot better than mechanical filters in this respect. You should change this type on a regular basis to keep fish happy.

A dirty carbon filter can leach out chemicals back out into the tank. 

The best way to know when to replace this filter is when the water begins to get a little cloud or a brown color. This means the carbon filter isn’t working anymore and you will need to replace it quickly. It is better to remove it than to wait until you have a new one as leaving it in the filter will mean that the dirt goes back into the water again and it could look worse than before the carbon filter was put in.



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