The Best Filter For Betta Fish: All Tank Sizes & Adjustable Flows

Bettas are particularly sensitive to currents in your tank so, amongst other factors, flow rate is key in finding the best filter for betta fish.

By Matt Thomas
Last updated on

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Best Adjustable HOB

AquaClear 20 Hang On Back Filter
AquaClear 20 Filter

Best For Community Tank

Penn Plax Cascade 500 Canister Filter
Penn-Plax Cascade 500
best filter for betta

Bettas are beautiful fish that need clean, clear water to thrive. But choosing the best filter for betta fish can be challenging, as not only does it need to provide excellent filtration, but you also need to be able to control the flow to avoid strong currents in your tank.

We’ve assessed some of the best filters for betta tanks and overall the AquaClear 20 Power Fish Tank Filter is our top choice for it’s adjustable flow rate and customizable, and easy to change filter media.

But perhaps you have a single betta in a 5 gallon tank, or maybe he’s part of a larger community aquarium? That’s why we’ve reviewed a range of different types, from sponge filters to canisters, so you can chose the best filter for your betta and your tank!

Just take a look at the list below!

  1. Best For Adjustable HOB: AquaClear 20 Power Fish Tank Filter
  2. Best For Small Betta Tank: Aqueon Quietflow AT10 Internal Power Filter
  3. Best For Community Tank: Penn-Plax Cascade 500 Canister Filter
  4. Best For Low Current: Hygger Aquarium Double Sponge Filter
  5. Best For Undergravel: Penn-Plax Clear-Free Under Gravel Filter
  6. Best For Easy Maintenance: Marina Slim S10 Power Filter

Best Filter For Betta Tanks Reviewed

We’ve spent many combined hours assessing some of the best filters for betta fish to help you make the right choice. You’ll find options from internal, to sponge filters, to canisters and the common theme is they’re all adjustable so you can get the perfect flow for your betta.

1. AquaClear 20 Power Fish Tank Filter

AquaClear 20 Hang On Back Filter

Photo: Chewy.com

  • Filter Type: Hang On Back
  • Dimensions: 5.0 (w) x 4.0 (d) x 6.25 (h) inches
  • Flow Rate & Aquarium Capacity: 100 GPH, for 5 to 20 gallon tanks (other sizes available)
  • Filter Media: 3 stage filtration – foam for mechanical, carbon for chemical, and BioMax rings for biological filtration
  • Best For: Adjustable HOB

The AquaClear 20 HOB filter is a perfect option for betta tanks between 10 and 20 gallons primarily due to it’s easily adjustable flow rate which can go down to 33 GPH. This will cycle a 10 gallon tank just under 4 times an hour, while reducing the current for your betta.

It also re-filters the water at a slower flow giving longer contact with the filter media, so you get excellent filtration with a lower current. It’s 5.0 x 4.0 x 6.25 inch size is very compact too, especially as most of it hangs off the back, leaving more room in the tank for your betta.

The AquaClear is a 3 stage filter and comes with Activated Carbon and BioMax rings which are excellent at removing ammonia and toxins to keep your water clean and clear. But as many owners point out, it’s also great for customizing with your own media too.

Overall the AquaClear is a great HOB filter if you want full control over your media and to be able to fully adjust the flow rate to give a perfect low current for your betta fish!

2. Aqueon Quietflow AT10 Internal Power Filter

Photo: Amazon.com

  • Filter Type: Internal
  • Dimensions: 2.75 (w) x 1.5 (d) x 6.5 (h) inches
  • Flow Rate & Aquarium Capacity: 28 to 58 GPH, for tanks between 5 to 10 gallons (other sizes available)
  • Filter Media: 3 stage filtration, dense foam for mechanical, activated carbon for chemical and BioGrid for biological
  • Best For: Small Betta Tank

The Aqueon Quietflow AT10 is an incredibly compact yet powerful internal filter. Whilst it’s rated for use in tanks up to 10 gallons we found it best for tanks between 5 and 10 gallons due to the power. There are also other sizes available for up to 40 gallon aquariums.

You can adjust the flow rate from 58 GPH down to 27 GPH, although the instructions aren’t the clearest, leading many owners to question whether the flow is indeed adjustable. The trick is to pull up the output nozzle and twist the telescopic pipe to reduce the flow.

Not only this but you can fully adjust the output flow direction giving you even more ability to reduce the current to get it perfect for your betta fish. And you can mount the 2.75 x 1.5 x 6.5 inch unit horizontally or vertically so it won’t take up much space in your betta tank.

The AT10 provides 3 stage filtration to get your water crystal clear, and uses Aqueon Replacement Internal Filter Cartridges which are easy to replace, although you do need to remove the filter from the tank.

3. Penn Plax Cascade 500 Filter

Penn Plax Cascade 500 Canister Filter

Photo: Chewy.com

  • Filter Type: Canister
  • Dimensions: 11.5 (w) x 9.0 (d) x 13.5 (h) inches
  • Flow Rate & Aquarium Capacity: 115 GPH, for tanks up to 30 gallons (other sizes available)
  • Filter Media: 2 fully customizable media baskets, includes 2 Poly Fiber Floss Pads, 1 Coarse Bio-Sponge, and 1 Bag of Activated Carbon
  • Best For: Community Tank

If your betta fish is part of a slightly larger 20 to 30 gallon community tank, then a small canister filter can be a great option. The Penn-Plax Cascade 500 is perfect as the 115 GPH flow rate can cycle a 30 gallon tank around 4 times an hour, but it’s also fully adjustable.

Both the inflow and outflow valves allow you to adjust the flow so you can slow the current to make it suitable for your betta. And the 2 customizable media baskets allow you to add your choice of mechanical, chemical and biological media to get your water clean and toxin free.

Many owners praise this as an excellent external filter given it’s large capacity and easy to use push-button primer, meaning you can easily remove air from the filter on start-up. But many note it’s best for 20 to 30 gallon tanks as it can be too powerful for a betta in a small tank.

4. Hygger Aquarium Double Sponge Filter

Photo: Amazon.com

  • Filter Type: Sponge
  • Dimensions: 6.0 (w) x 1.8 (d) x 9.0 (h) inches
  • Flow Rate & Aquarium Capacity: flow dependent on air pump (purchased separately), for tanks 10 to 40 gallons (other sizes available)
  • Filter Media: 2 sponge filters for mechanical and biological filtration, ceramic media balls for further bio filtration
  • Best For: Low Current

The Hygger Aquarium Double Sponge Filter is an excellent option if you want to keep the current as low as possible for your betta but still achieve great filtration in a small tank. The 6.0 x 1.8 x 9.0 inch size means it won’t take up much room in a 10 gallon tank.

You need to attach an external air pump (purchased separately) to run the filter via the 4mm hose, but as it’s a sponge the current is minimal for your betta. The two sponges capture large and fine particles, as well as allowing beneficial bacteria to colonize and break down toxins.

This, combined with the ceramic media balls positioned under each sponge, means you get excellent biological filtration leading to clean, clear water for a smaller tank. All with hardly any flow for your betta!

5. Penn-Plax Clear-Free Under Gravel Filter

unergravel filter

Photo: Chewy.com

  • Filter Type: Undergravel
  • Dimensions: (base plate) 19.0 (w) x 9.5 (d) x (lift tube) 12.75 (h) inches
  • Flow Rate & Aquarium Capacity: flow dependent on air pump (purchased separately), for 10 gallon tanks (other sizes available)
  • Filter Media: 2 Replaceable Filt-a-Carb Activated Carbon Media Cartridges for chemical filtration, (substrate used for mechanical and biological filtration)
  • Best For: Undergravel

An undergravel filter can be a good option for your betta, as depending on the power of the air pump you use it does not generate too much flow. The Clear-Free from Penn-Plax is great for 10 gallon tanks.

It comes with two plates that sit on the base of your tank, so you’ll need to check your measurements. You can use the two plates together at 19.0 x 9.5 inches, or use just one for a smaller tank at 9.5 x 9.5 inches.

The flow is dependent on the air pump you choose (purchased separately), but as the water is drawn down through your gravel and returned by the adjustable lift tubes you can achieve a gentle current for your betta.

While most undergravel filters rely on your substrate for mechanical and biological filtration, and the Clear-Free does the same, it also comes with Filt-a-Carb Activated Carbon Media Cartridges in the outflow tubes. This gives extra chemical filtration to remove ammonia and other toxins too!

Overall this is a quiet, low-flow filter that can be perfect for your betta in the right size tank. But bear in mind that whilst it’s easy to set up under your substrate in a brand new tank, you’ll need to siphon your gravel at least weekly to remove debris and keep your tank clean.

6. Marina S10 Power Filter

Marina S10 Hang On Back Filter

Photo: Chewy.com

  • Filter Type: Hang On Back
  • Dimensions: 6.50 (w) x 3.70 (d) x 7.30 (h) inches
  • Flow Rate & Aquarium Capacity: 55 GPH, for tanks up to 10 gallons (other sizes available)
  • Filter Media: Bio-Carb Cartridge for mechanical and biological, Bio-Clear Zeolite Cartridge for chemical filtration (sold separately)
  • Best For: Easy Maintenance

The Marina Slim S10 Power Filter is a compact HOB filter that’s a great choice for a small betta tank up to 10 gallons. At just 3.70 inches deep it only protrudes around 2 inches from the back of your tank so you can get your aquarium close to the wall if you’re short on space.

Although this filter has a flow rate of up to 55 GPH and can cycle a 10 gallon tank just under 6 times an hour, it’s easily adjustable, making it a fantastic option as a low current filter for your betta. It also includes a pre-filter sponge to stop delicate fins getting trapped in the intake.

Owners praise this filter for being easy to customize and very easy to maintain. There are different cartridges like the Bio-Carb with Ceramitek to help colonize beneficial bacteria, and Bio-Clear containing zeolite to absorb ammonia and keep your tank crystal clear.

Why Your Betta Needs The Right Filter

Betta fish are highly sensitive to the conditions in your tank, and need very clean water with ammonia and nitrate levels being kept as close to zero as possible. Whilst it is possible to achieve this without a filter, in reality for most people it’s very impractical.

red white blue betta fish

Maintaining the right water conditions without a filter would need you to do almost a full water change around twice a week, and thoroughly clean all the equipment and decor. With the right filter, you’d only need a partial weekly water change and a gravel siphon with a light clean.

How Is A Filter For Betta Fish Used?

Aside from keeping your water clean, the best filter for betta fish will perform a number of other tasks with added benefits: 

  • Filter Materials And Toxins:  In addition to removing larger waste matter, your filter breaks down harmful toxins, including ammonia, to leave your water safe for your betta.
  • Provides Aeration: Whilst betta fish can breathe air from the surface using their labyrinth organ [1], they have adapted this to survive times when their habitats dry up. To thrive, betta’s prefer well oxygenated water which a good filter will provide [2].
  • Circulates The Water: Whilst circulation is important to aerate the water and prevent stagnation, it’s critical that your filter has a low flow. Strong currents will stress your betta [3], and so the best filter for bettas will have an adjustable flow rate.
  • Helps With Consistent Temperature: Bettas are sensitive to temperature changes and prefer a range between 75°F to 81°F [4]. As your filter circulates the water it will help keep the temperature consistent throughout, particularly in a larger tank.

What Type Is The Best Filter For Betta Fish?

The best filter for betta fish should have similar features as for any aquarium. But as bettas cannot tolerate a high current, a low-flow or ability to control the flow rate is particularly important whichever type you choose.

  • Hang On Back Filters: Small HOB filters can be great if you have a single betta in a 5 gallon tank as they hang outside saving space. But as HOBs return the water as a cascade, and many are powerful, do choose one with an adjustable flow rate.
  • Sponge Filters: These filters produce a very low amount of current which is perfect for betta fish, but can only deal with a small bioload. So again, if you keep a single betta in a small tank they can be a great option, but are less effective in a larger well-stocked tank.
  • Under Gravel Filters: These sit under your gravel and draw water through before recirculating at the top. They are great in smaller betta tanks and don’t produce much current, but as they use your gravel as the filter media you’ll need to siphon regularly.
  • Internal Filters: Internal power filters are another fantastic option for your betta, as long as you choose one with an adjustable flow rate. Although they sit inside your tank, they tend to be very compact and offer mechanical, chemical and biological filtration.
  • Canister Filters: A canister can be an option for your betta in a larger community tank. They provide excellent filtration and you can customize the media, but are pressurized so can create a strong current. So again choose one with an adjustable flow.

How To Choose The Best Filter For Betta Fish

The type of filter you choose will depend on a number of factors. Let’s look at the main ones you need to consider when choosing the best filter for betta fish tanks.

betta fish with yellow fins

Tank Size And Filter Capacity

Tank size is a key factor in choosing the best filter for betta fish. Your filter should have a capacity appropriate to the volume of your tank. While there’s no set rules, a smaller HOB, internal or sponge filter is often a good choice for a nano tank with a single betta.

If you have your betta in a slightly larger community tank up to 30 gallons, then a small canister filter may also be a good option. Most manufacturers will say what volume of tank their filter is designed for, but if it’s internal do ensure it will physically fit in your aquarium too!

Adjustable Flow Rate

A filter’s capacity is defined by it’s flow rate, measured in gallons per hour (GPH). As a general rule your filter should be able to cycle all the water in your tank around 4 to 6 times per hour. So for a 5 gallon betta tank you’ll want a filter with a flow rate between 20 to 30 GPH.

But in choosing the best filter for betta fish, you’ll also want a filter with an adjustable flow rate so you can reduce the current if needed. Most filter types can be adjustable, it just depends on the individual model. So do make sure to check the particular one you are looking at.

Filtration Stages And Media

As with most filters, the best filter for betta fish tends to be one that is ‘3 stage’, meaning that it uses mechanical, chemical and biological media:

  • Mechanical Filtration: Typically the first layer of media, this is often sponge or filter floss which traps debris and particles from the water.
  • Biological Filtration: This layer consists of media such as porous ceramic which allows beneficial bacteria to colonize. These bacteria cleanse the water by breaking down ammonia from fish waste into nitrite, and then less harmful nitrate.
  • Chemical Filtration: Substances like carbon form the third filtration stage. Carbon absorbs ammonia and other toxins to further cleanse the water for your betta.

Often with filters designed for smaller betta tanks, all three of these media can be present in easy-to-change filter pads depending on your filter type. Or if you have a single betta in a tank you could use a 2 stage sponge filter, due to the smaller amount of waste produced.

Ease Of Use And Maintenance

Along with regular water changes, correctly maintaining your filter is one of the best ways to ensure a healthy tank and keep your betta in great condition. When looking for the best filter for betta fish you’ll need to consider how easy it is to access and maintain.

Many small aquarium filters that are suitable for betta tanks come with easy-to-use replacement cartridges. Sometimes these have separate biological or chemical pads meaning you can change them at different times and have more control over your water chemistry.

Noise Level

Depending on the type, some filters can be louder than others. Often the quietest aquarium filter tends to be a HOB or canister, but it also needs to be the best filter for betta fish too. Internal filters are also quite quiet as the pump is submerged.

Filters with external air pumps, such as sponge filters, can be noisier especially if the pump vibrates against the table or aquarium stand. You can dampen this by using a leveling mat or pad though. 

Price And Reliability

As the best filter for betta fish can be one of several types, you can choose one to suit your budget. Canister filters, for example, are more expensive but a good option for a larger tank. But if you have a smaller budget there are plenty of great HOBs or internal filters.

Whichever type you choose, you’ll want to pick one from a trusted brand that is reliable. One of the best ways of checking this is to read reviews from owners on sites like Amazon. This is a great way of ensuring your chosen filter is going to perform and last well.

Our Verdict

We chose the AquaClear 20 Power Fish Tank Filter as the best betta filter for betta tanks, especially in a smaller aquarium or if you only have a single fish. The filter’s adjustable flow rate and ability to achieve excellent filtration at a slow setting make it perfect for bettas.

In a larger community tank the Penn-Plax Cascade 500 Canister is a great choice, particularly as the inflow and outflow valves are adjustable giving full control of the flow rate. But depending on your needs, any choice from this list would work equally well for your betta!

FAQs

Here are the answers to some of the most frequently asked questions when it comes to finding the best filter for betta fish.

Can A Filter Be Too Strong For A Betta Fish?

Yes. Betta fish are sensitive to current and prefer low flowing water that reflects their natural habitat [5]. So always choose an adjustable filter with the right capacity for your tank size.

What Type Is The Best Filter For Betta Tanks?

Adjustable flow canister filters like the Penn-Plax Cascade 500 are perfect for your betta in a larger community aquarium. HOBs, internal or even sponge filters are great for a single betta.

Why Does My Betta Fish Stay Near The Filter?

It’s very likely that he is stressed by too stong a current and so is staying close to the filter to avoid the flow [6]. So reduce the flow rate by adjusting it or using a baffle.

How Do You Slow The Current Of A Betta Filter?

If you filter doesn’t have an adjustable flow rate you can reduce the water intake current by covering it with filter sponge. You can also baffle the water output with mesh to reduce the flow.

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AUTHOR
Matt Thomas
Matt has been keeping fish since junior high when he used to look after his parent's tank. He loves guppies, cichlids, and his crowntail betta named Bobby.

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