Are Canister Filters Good For Saltwater Tanks?

This article is all about using canister filters on a saltwater tank.

Canister filters are a very basic and effective method of filtration most commonly used on freshwater aquariums.

Using a canister filter on a saltwater tank is a big topic of conversation and there seem to be many different views about it.

Regardless if you are keeping a freshwater or saltwater tank, it’s important to incorporate effective methods of filtration to keep your tank clean and healthy.

A canister filter is just one way to filter an aquarium.

But is it effective on a saltwater tank?

Let’s find out.


Can you use a canister filter on a saltwater tank?

Yes, you sure can. Canister filters offer several stages of mechanical, chemical, and biological filtration for your saltwater tank.

Although these filters are great for many uses, there are better methods of filtering a saltwater tank.

Most people with saltwater tanks who either decide on not using a sump system or can’t use one will choose to run a canister filter.

The problem with using canister filters on saltwater tanks is they require a lot of regular maintenance to prevent detritus build up inside the filter. This detritus will lead to nitrate and phosphate issues which can cause poor water quality and is harmful to livestock.

You can run a successful reef tank with a canister filter. But be prepared to clean and maintain it quite often. Also, canister filters are better left for smaller tanks. They are just not big enough to filter a large-sized saltwater tank, a sump system will be much more effective.

You can always use a canister filter as an add on or secondary filtration if you have a large tank.


How do canister filters work?

Most canister filters are designed with several baskets inside to hold different types of filter media. There is an internal pump housed inside that will draw water from the main tank and return it back as filtered water. The water will be drawn through the various stages of filtration including bio media, filter floss, carbon, and any other media you choose.

Canister filters have an inlet and output tube, connected with tubing to allow water to run into and out of the filter. These filters will normally sit inside your stand and out of view. They are available in many different sizes and have various flow rates that should be matched to your tank size.

As mentioned, the problem with canisters is the amount of cleaning and maintenance required. It’s not a huge concern with freshwater tanks as it is for saltwater tanks. Build up of detritus and waste is not a good thing for saltwater tanks especially reef tanks where high water quality is important.

Not only do you need to clean them quite often, but they can be difficult to take apart and clean out. It can be a tedious task. Canister filters will be full of water when it’s time to clean which is a recipe for a wet floor upon disconnect.

Think of how often you need to clean filter socks inside a sump. They should be cleaned or replaced a few times per week to remove the detritus and waste that is collected. If this is left to build up inside a canister filter, your water quality will be directly affected in a poor way.


How often should you clean a canister filter?

When I had my last canister filter on my reef tank, I was cleaning it 2 times per week. You can get away with once per week, but it will depend on your bioload, size of the tank, filter contents, etc. It doesn’t take long to start getting frustrated with cleaning out the filter so often.


Using a canister filter on a FOWLR tank

If you are keeping a FOWLR tank, canister filters do a great job removing debris and keep your water clear. Reef tanks require better water quality than a fish only tank so using a canister filter on a fish only or FOWLR tank is better suited than on a reef tank.


Canister filters vs sumps


Image credit: Marine Depot


A sump system on a saltwater tank has many advantages over a canister filter. Sump tanks are considerably larger which increases the overall water volume of your system. This will help keep your water parameters stable. Sumps have more space available for bacteria to colonize and be effective. Canister filters are best kept for smaller tanks when a sump is not practical or possible. Other than the filtration advantage, sumps have many more benefits and should be used if possible.



So to answer the question, are canister filters good for saltwater tanks? No, they are not a good choice when there other options available. That’s not saying they can’t be used, because they can. You just need to be aware of the effect on water quality if they are not cleaned on a regular basis. This includes replacing filter media and padding as needed. Canister filters get very dirty fast which is not what you want on a saltwater tank. If you have the option of using a sump system, your tank will thank you for it.