Are Canister Filters Good for Saltwater Tanks?

We know we need to filter our saltwater tanks, but is it necessary to buy an expensive sump system when you already own a canister filter? Saltwater aquariums require mechanical, biological and chemical filtration – what’s the best way to do it?

Canister filters have the capacity to handle all the filtration needs of an aquarium, but the ‘nitrate factory’ fear and required maintenance cause many saltwater hobbyists to opt for alternative options.

To help you decide whether to use a canister filter or an alternative system, this article will answer the question of can I use a canister filter for a saltwater tank?​

Using a Canister Filter as the Sole Filtration System

Many people use a single canister filter as the sole means of filtering the aquarium, and as long as it's kept clean and maintained regularly, there's no reason you need to use it in conjunction with other systems (but it's arguably a better option).

Regarding mechanical filtration functionality, it draws in small free floating pieces of particulate matter and effectively removes it from the water. However, you might prefer to use a different device for mechanical filtration such as an under gravel filter.

It's also excellent for getting rid of those small white specs you see floating in your tank, or to put it more technically, the copepod and amphipod larval blooms. But overall, these filters are – in my opinion – best used during tank cleaning for their mechanical filtration functionality.​

When you need to improve the quality of your saltwater, you’ll need a system for chemical filtration. You can bolster your canister’s mechanical filtering ability by placing granular activated carbon in the media chamber which will help eliminate odors and contaminates.

Many of these filters are designed mainly for their biological filtering capabilities, and they usually work quite well with smaller aquariums. Though in my opinion, you’d be better not to rely on the canister solely for larger tanks.

Using a Canister Filter with Multiple Filtration Systems

Canister filters require cleaning at least once a month to maintain their effectiveness, and that’s why you might consider using it in conjunction with other filtration systems to avoid problems that can occur when a filter gets too clogged.

I would certainly suggest using at least one other system for biological filtration such as live rock or a wet/dry trickle filter. Most canister filters don't have the capacity for the amount of organic media needed to eliminate water contaminants effectively.

At the very least, you should use two hang on canister filters for medium sized tanks, but I'd suggest going for another source of biological filtration in conjunction with canister filters for larger tanks.​

I can imagine that saving cash is a huge factor affecting why you’re wondering about the usefulness of canister filters for saltwater aquariums, but I’d suggest you at least consider a sump system if you want a durable single filtration system.​

Considerations - Water Flow Rate

You can usually find out the flow rate of your filter by checking the manual or instructions, but bear in mind that the measurement you read is usually based on the filter not having to pump water upwards.

If you use extra materials – which could include sponge, floss or micron pleat cartridges – in the media chamber in a bid to enhance your canister’s filtering capabilities, you’ll likely diminish your filter’s flow rate and actually reduce its effectiveness.

If you plan to store your canister at the bottom of your aquarium, the head pressure is likely to reduce its maximum water flow and consequently, also negatively affect its usefulness. Additionally, your item might have to work harder and result in higher energy bills.​

Consideration – the ‘Nitrate Factory.'

As I've already touched on, one of the problems associated with canister filters is how often they require cleaning to avoid a nitrate issue. Nitrate issues are most commonly caused due to debris and detritus build up that rots and decomposes inside the filter.

Unfortunately, this ‘nitrate factory’ effect is usually unavoidable, especially in saltwater aquariums. You should try to keep your nitrate levels in saltwater tanks below 5 ppm, as higher levels than that can result in excessive algae growth.​

A manageable amount of algae growth is actually quite healthy for your aquarium, but too much results in high levels of phosphate, and that can be very unhealthy for your fish – not to mention, algae can be difficult to eliminate once the problem is already out of control.​

Maintenance

The biggest factor which affects those in the ‘no’ camp regarding the question of ‘can I use a canister filter for a saltwater tank?' is its need for regular cleaning. You might have been keen on the idea of a canister if you're a reef beginner, but maintenance is required monthly.

You can learn how to clean a canister filter to use it for your aquarium, but it involves breaking down the components, cleaning individual parts before putting them back together again. To prevent algae growth and nitrate problems in saltwater, you'll need to clean it often.

If you neglect to stay on top of maintenance, you also run the risk of other harmful contaminants being pumped back into the tank – on top of the algae, phosphate, and nitrate risk.​

So, are canister filters suitable for saltwater tanks? If you’re just getting over your freshwater days and have a canister filter to spare, I would say you can go ahead and use it in your saltwater aquarium until you can change to a different system.

However, if you’re a passionate saltwater aquarium hobbyist, I’d suggest installing a sump system because I think they boast superior efficiency compared to any other system, but they’re not the cheapest or simplest filters to install.

Do you agree with my opinion? Is there anything I’ve missed out? What are your experiences with using a canister filter for a saltwater tank? Submit a comment below and share what’s on your mind.​

The Verdict


So, are canister filters suitable for saltwater tanks? If you’re just getting over your freshwater days and have a canister filter to spare, I would say you can go ahead and use it in your saltwater aquarium until you can change to a different system.

If you intend to use canister filters continuously, you could opt for a product such as the API FilStar XP-XL series which is already loaded with features to take care of all mechanical, biological and chemical filtration systems.

However, if you’re a passionate saltwater aquarium hobbyist, I’d suggest installing a sump system because I think they boast superior efficiency compared to any other system, but they’re not the cheapest or simplest filters to install.

Do you agree with my opinion? Is there anything I’ve missed out? What are your experiences with using a canister filter for a saltwater tank? Submit a comment below and share what’s on your mind.​

About the Author Joan Smith

Loves fish and taking care of them

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