Setting up a canister filter for a saltwater aquarium is easy. Most people prefer to use a sump for filtering saltwater aquarium water, while other saltwater aquarium hobbyists enjoy the ease of a canister filter to keep their saltwater aquarium water clean.

Filtration in a saltwater aquarium is important in keeping your fish and all inhabitants of your saltwater tank healthy.

There are many pollutants in your saltwater aquarium that must be removed. Some of these pollutants are fish waste, uneaten food and the remains of animals that passed away in the salt water tank.

2 Types of Filtration for a saltwater aquarium

The first type of filtration for a saltwater aquarium can be done with a canister filter.

Canister filters are smaller versions of a filter you see on a neighbor’s pool in their backyard.

A canister filter is nothing more than a canister containing a pump that syphons water from your saltwater aquarium through the filter media in the canister, then back out to your saltwater aquarium.

The canister filter can be tucked neatly and out of site, under your saltwater tank’s stand. Canister filters require an outlet to run.

Make sure no water comes into contact with the outlet where the canister filter and other aquarium equipment is plugged in.

There are 2 tubes attached to the top of the canister filter. One tube sucks water in from your saltwater aquarium to be filtered through the filter media inside the canister, and the other tube puts the filtered water back into your saltwater aquarium.

A canister filter should be cleaned weekly when you do your saltwater tank water change.

Along with removing 10% of your aquarium water and replacing with new saltwater, you need to remove all filter media and replace with new filter media inside your canister filter.

The filtration process for your saltwater aquarium water happens inside the canister filter.

You can put whatever filter media you want inside the canister filter to remove fish waste and uneaten food from your saltwater tank.

It is important to replace the filter media (foam) weekly in your saltwater tank’s canister filter.

Replacing filter media in your canister filter is important to ensure your saltwater is being filtered properly and not just flowing through dirty filter media.

Some saltwater aquarium hobbyists insist on putting bio balls or ceramic rings inside the canister filter. These items will house beneficial bacteria, which is needed for a saltwater tank to thrive.

I’ll let you in on a big secret!

Not only are these extra items (bio balls or ceramic rings) not needed in a filtration system, they actually cause more problems for your saltwater aquarium.

Only use foam filter media in a canister filter

As mentioned above, some people choose to add bio balls or ceramic rings to allow beneficial bacteria to breed. This is not necessary, as beneficial bacteria lives all over your saltwater tank!

Beneficial bacteria lives on your sand bed, on the rocks in your saltwater tank (this is why it’s called live rock), deep inside the rocks, on the glass, and basically everywhere saltwater is located in your aquarium.

Your canister filter should be used ONLY as a filter! Foam filter media that is replaced weekly is the best way to filter your saltwater aquarium!

You can buy reusable thick foam for your canister filter. All you need to do during your weekly water change is rinse throughly (not tap water) and replace.

Any extra items such as bio balls or ceramic rings are never recommended for a saltwater aquarium, as they will only catch and hold on to fish waste and uneaten food.

As fish waste and uneaten food get trapped in bio balls or ceramic rings, they begin to rot. This rotting is toxic to your saltwater aquarium.

Fish waste and uneaten fish food breaks down into ammonia, then nitrites and nitrates. Your saltwater tank will see a rise in nitrates, which are bad or your aquarium and the inhabitants in it.

These toxins need to be removed weekly via water changes and replacing the filter media (foam.) What good is a canister filter if ceramic rings or bio balls are kept inside of it (trapping uneaten food or fish waste?)

The second type of filtration for a saltwater aquarium can be done with a sump.

I will go into more detail on sumps in another post, but wanted to show you what a sump looks like.

A saltwater aquarium sump is nothing more than a small fish tank that sits under the stand of your saltwater aquarium.

Water from your saltwater aquarium flows to the sump via one or two holes in the bottom of your saltwater tank via 1″-2″ tubing.

Saltwater aquarium sumps come in many shapes and sizes but all serve the same purpose; they filter your saltwater aquarium water.

There are various chambers in a saltwater aquarium’s sump, with each being responsible for a different part of the filtration process.

Once the filtered water reaches the last sump, it is returned to your saltwater aquarium via a large pump, that also sits submerged underwater in the sump.

In this image you see the sump (miniature fish tank) inside the stand of the saltwater tank. Water flows down from the main saltwater tank into this sump, is filtered through the various chambers of the sump, and pumped back to the main saltwater tank above.

As you can see, this saltwater aquarium owner chose to have some rocks in one of the chambers, which is housing the beneficial bacteria for the saltwater tank.

Some saltwater aquarium owners put sand in one of the chambers, live rock or foam, to filter out toxins in the saltwater tank.

That large device on the left side of the sump is called a protein skimmer. A protein skimmer skims the pollutants out of the water, which are collected in the collection cup at the top. The collection cup is easily-removed so you can dump out the nasty toxic water which contains the broken down fish waste and uneaten food from the aquarium.

If this was my sump, I would have foam filtration in the first chamber to capture all the large solids from the water, then the 2nd chamber would have more foam to polish the water and remove extra waste, with the 3rd chamber having the protein skimmer to collect any molecular matter from the water after being filtered by the foam blocks in chambers one and two.

I will write more about saltwater tank sumps in another post.

There are no hard set rules to setting up filtration for a saltwater aquarium whether you use a canister filter or a sump. The most important thing to remember with saltwater aquarium filtration is to replace or clean all filter media weekly!

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Thanks for reading!

Steve