We hope that this page will tell you everything you need to know about finding the right filter for your betta aquarium. If you already have a filter, we would love to hear about the filtration setup that you’ve created, so please let us know in the comments.
This article mainly refers to choosing a filter for a tank with a single betta. For larger setups, you may need to look at a slightly different filtration system, although most of the logic still applies.
If you’d like a bit more information on how a filter works, see our betta filtration article, which includes diagrams, defines the terminology that we use, and answers some common questions.
What’s the Best Filter for a Betta?
There is no particular filtration unit that is ‘the best’ for a betta. There are several factors to consider when choosing a filter, including size, output rate, plants, tank mates, and the extent to which it will keep your aquarium clean. Therefore the ‘best filter for a betta’ will depend on your aquarium set up.
In this article we will talk about the different scenarios in which you could be choosing a filter, and present some advice that should help you to make a decision when it comes to buying. We do recommend three different filters at the end of the article. Scroll straight down if you want to skip straight to that section, although it is useful to consider the recommendations within the context of the rest of this article, and to some extent our other article on filtration.
Something to bear in mind when it comes to betta care (and fish keeping in general) is that there is no set way of doing things. There are certain practices that you should follow, but betta keeping also involves some degree of experimentation. This is very true of filtration — there are different things that you can try in order to achieve the optimum solution for your particular aquarium. What we’ve included below is advice based on our own experience, but we do urge you to do further research yourself.
We love to hear about the setups that other people have created, so do let us know in the comments about your filtration system, or any other aspect of betta keeping that you would like to talk about.
The best filter for a betta will have these features:
- A slow output/current so the fish can relax and swim easily in the aquarium.
- An easy-to-remove cartridge system – the filtration media can easily be replaced when needed, and on an individual basis.
- Removal performance – will the filter be able to do it’s job given the size of your aquarium? Will it be capable of cycling the aquarium successfully and will it remove unwanted chemicals and waste?
- Filter media – does it have more than one media? In some cases, having all three types of media (mechanical, bio, and chemical) is better. In other cases (such as for optimal plant growth), just having one or two is better. We cover this in more detail below.
- Reliability – Will the filter consistently perform? Is it likely to clog-up or break down? Is it manufactured well? Always take other people’s’ experience with specific products into account when choosing a filter.
Other Important things to consider
The size of your aquarium. You may pick up a filter that is perfect in terms of the filtration mediums that it offers, but has a strong output rate. A strong output rate may not be an issue if you have a large aquarium, but can be a problem if your tank is small. In a large aquarium there will be areas where a current does not affect the water, nor create ripples on the water’s surface, which will be a suitable environment for your betta as there will be parts of the aquarium where it can escape the current, and therefore it won’t be stressed.
Does the filter have an adjustable output? It’s important to adjust the output of a filter in relation to the aquarium size. If you add a filter with a strong output to a small aquarium, it will stress your betta. It’s therefore important that your filter either has the option for the output to be adjusted, or that you can modify the filter yourself (see our article on filter baffling) in order to control the output.
Aesthetics & Practicality. Others features that are not important to the well-being of the fish but may be important to the keeper are aesthetics and practicality. Does the filter look good? Will the filter be noisy? Will it disturb you if the filter were to make noise because of trickling, the sound of the pump, etc.? These concerns are of course secondary to the well-being of your fish, but they are still worth taking into consideration when you buy a filter.
The typical aquarium filtration system will be comprised of three different mediums; biological, mechanical and chemical. Each one of these mediums does its own job, you can read about how they work on our filtration page..
Ideally you want to be able to replace each type of media individually because each medium needs to be replaced at different intervals. This is why a filter with separate inserts is often preferable to a filter that uses cartridges, which we explain in more detail below.
The optimum filter for a betta will contain all three mediums, although a filter with only 1 or 2 of the mediums can still perform well depending on your set up. Whilst the typical filter will be shipped with all three mediums, there are some filters that are only shipped with one or two. We’ll talk about this in more detail below, but first of all let’s look in more detail at why a cartridge filter isn’t always optimum.
Why a cartridge isn’t always optimum
Most aquarium filters these days come with all 3 filtration mediums, which is referred to as 3-stage filtration. The three mediums are known as mechanical, biological and chemical. It’s pretty standard for any built-in aquarium filter to have all three mediums, with each being easily removable and replaceable.
You may, however, come across a filter that has a replaceable cartridge. The cartridge will be manufactured by the aquatics company to fit the filter in question. Beware, though; replaceable cartridges aren’t always the best option because they can be impractical when it comes to changing the mediums at different intervals. Whilst they have been manufactured with the convenience of the fish-keeper in mind (because theoretically it’s easier to just slot in a new cartridge than it is to replace each medium individually), this can limit the control you have over the chemistry of your water. In our list of recommended filters below, we have taken this into consideration.
If you want maximum control over your betta’s water quality, it’s best to aim for a filter that has removable and replaceable individual inserts.
Filter Cartridges and Maintenance
Some filters will need to have their cartridge or inserts changed every month or so. The cartridge can vary from filter to filter, but typically a replaceable-cartridge filter will have a carbon or carbon-mixed cartridge that will need replacing periodically. Carbon is a great medium for removing toxins from the water, but if it’s not removed on a monthly bases it can actually create a backlog and the toxins can leak back into the aquarium.
The sponge insert can vary in size in any filter. When it should be rinsed/cleaned will be dependant on the amount of livestock in your aquarium. The more livestock, the more often it should be rinsed. The mechanical sponge is a place for beneficial bacteria to flourish in the filter, that’s why it’s best not to replace it. In fact, it only needs to be replaced if it gets withered over time. It should only ever be removed, rinsed (with freshwater) and reinserted. Most mechanical filtration media is hardy and isn’t designed to wither, and it usually lasts for years at a time. The same goes for biological media — nothing lasts forever but it should rarely be replaced, if at all. Over time biological media may become decrepit, but it will take years for this to happen.
Aquatics companies manufacture cartridge filters in different ways, but it’s generally agreed upon that a cartridge filter is second best to a filter that allows inserts for separate mediums. See our filtration page for definitions of this terminology and explanatory diagrams.
Choosing a filter
Now that we’ve covered the various aspects of filtration that you need to be aware of, let’s have a look at the scenarios in which you may be choosing a new betta filter.
Scenario 1: Choosing an aquarium with a built-in filter
If you’re buying a tank that comes with a filter built-in, you need to do some research to check that both the filter and tank will be suitable for the setup that you want. For instance, you may wish to check that the filter has a cartridge with separate inserts for each medium, as opposed to two mediums combined within one cartridge. This shouldn’t be the case for most tanks that come with a filter built-in, but it’s worth checking.
The majority of standard freshwater aquarium filters, especially those pre-fitted in an aquarium, tend to contain a biological, mechanical and chemical medium. From our experience, most of the in-built filters in the the Fluval freshwater aquarium range have all 3 mediums in their filtration. This will work great so long as you take into consideration how each medium affects the chemistry of the water.
The typical filtration system should come with a carbon insert. The carbon removes CO2 from the aquarium water, along with any other unwanted chemicals. This insert should be replaced every month or two. Aquarium plants love CO2 — they need it to respirate (photosynthesis). When keeping aquarium plants, it’s also a great idea to give them a chemical plant feed. Not only will carbon remove a substantial amount of CO2 from the water, but it will remove any chemical feed as well, so having a carbon insert in your filter is not a great idea if you want to encourage plant growth.
If your filter has sponge, bio media and carbon inserts, you could replace the carbon insert with more sponge or bio media if you plan to keep live plants. When removing the carbon from the filtration, the plants will counteract this and act as filtration themselves. Aquarium plants are a great natural filter. You can read about this in our plants article.
To give you a real-life example, we bought the Fluval 19L for our current betta, Naan. We wanted to be able to remove the carbon (the chemical medium) from the filter in order to encourage optimal plant growth. This is easily possible with the filter that’s built into the Fluval 19L, which is one of the reasons that we chose it. The built-in filtration is mechanical, bio and chemical. It comes with a sponge insert + 2 inserts: one for a bio sack and the other for a carbon sack. The carbon sack can easily be removed or replaced, which is what we did with ours. Basically the Fluval 19L gave us flexibility. It’s a great ‘works out of the box’ solution for betta keepers. You can remove the carbon if you want plant growth, or you can leave it in if you don’t intend to keep live plants and would prefer to keep the chemical medium.
Another reason that we like the Fluval 19L is because its filter comes with an adjustable output. The output on its lowest setting, combined with the 19L volume of the tank, creates a stress-free living space for a betta. The output nozzle is also adjustable, so it can be angled in a particular direction in order to further control the location and level of the current.
Remember, a betta fish is hardy and can live happily in various water conditions, but some other critters can be quite particular when it comes to an aquarium environment. A betta fish could live happily with just a sponge filter, provided that you replace the insert every month or so and carry out regular water changes. If you plan to keep other inhabitants with your betta, you may need to invest in a filter that can sustain a suitable water condition for the whole ecology of the aquarium. This also brings up the fact that the more critters you have in the aquarium, the more waste there will be, meaning more ammonia, nitrites and nitrates will occur.our filter needs to be able to handle this.
Scenario 2: adding a filter to an existing aquarium
The other scenario is that your tank does not have a filter built-in, in which case you need to choose one to add to it. Which filter you choose will dictate the amount of control you have over replacing the three filter mediums individually. For example, if you choose a filter that uses an all-in-one cartridge, you may be forced to replace the biological medium at the same time as the chemical medium. This isn’t ideal — we explain why in more detail below. If you choose a filter that houses its media in separate inserts (or has a cartridge that can be modified so that you can replace the mediums at different intervals), you maintain the ability to replace them individually and ultimately this provides more control and flexibility.
There are quite a few great value aquariums on the market that are manufactured specifically with bettas in mind. This means that they come with a filtration unit that’s also great for bettas in terms of size, practicality and filter mediums (you can view some examples aquariums in our best betta tanks article). This may not be the case when buying a separate filter for your betta with the intention of adding it to an existing aquarium. It’s certainly not impossible, but there are a few factors that you need to take into consideration.
For example, if you’re adding a filter to your aquarium, it can be a challenge to find a suitable filtration unit for a water volume that’s less than 15L that won’t create a strong current and that won’t be bulky in the aquarium. This is yet another reason why it’s best for you to keep a betta in an aquarium with a capacity of 15L or more.
Below we have listed some good filters for betta tanks, and we explain how they work in regards to replacing the three different filter mediums. We’ve also listed some of the other pros and cons so that you can choose the appropriate one based on your setup and budget.
Filters that we recommend
Hopefully we’ve explained enough of the theory behind betta filtration that you can now make an informed choice about choosing a new filter. While it’s difficult to simply recommend the best filter for a betta, the three choices that we present below take into account the following:
Reliability, durability – does it do a good job?
Media replacement – are the mediums easy to rinse/replace on an individual basis?
Output – does it create a strong current? does it disturb the surface of the water? If so can it be baffled easily?
Size – will it fit into a 15L aquarium comfortably?
Noise – how much noise does the filter make? Does it become noisy after extended use?
Hagen – AquaClear 20 Power Filter
If you want a quiet filter this is probably as good as it gets (check it out here on Amazon). No filter is completely silent, but the Hagen AquaClear 20 Power Filter does a pretty good job of keeping noise to a minimum.
Another perk of this filtration unit is that it doesn’t use an all-in-one cartridge – you can control and replace each medium individually, which is great for keeping a consistent water quality.
- Very quiet, produces little noise and will continue to do so if maintained properly. If the aquarium water level is kept consistent the output will make no noise or trickle.
- Independent medium access. The filtration media can be replaced individually.
- 3 stage filtration
- Mechanical media does not need to be replaced (like most cartridge filters) and can simply be rinsed with freshwater and returned.
- Hang-on filter; it cannot be submerged and may not be compatible with an aquarium with a fitted hood.
- Unadjustable output – the water output could do with being a bit weaker in order to make it more comfortable for a betta, but depending on the size of your aquarium this may not be a problem. It’s frequently noted by users that it’s easily baffled, so output current can be easily reduced.
- It’s considerably bulky, but the filter only partially sits in the aquarium, so doesn’t actually affect the water volume. It may however be difficult to fit to a smaller aquarium.
The smallest model is for a 20L aquarium, the largest model is for a 50L aquarium.
Hagen Elite Stingray 10 Underwater Aquarium Filter
This filter can be fully submerged and does not need an run-0ff to perform properly (check it out here on Amazon). No run-off means no output hitting the water’s surface. It has a very unique shape compared to other filters – the aesthetics of it have been a topic of hot discussion among fish keepers.
- Considerably more quiet compared to other internal aquarium filters.
- Can sit in the aquarium fully submerged, meaning it can be used in an aquarium with a fitted lid or hood.
- Reasonably priced for what you get.
- It does a good job at keeping the water clear, especially if the filter is maintained and the cartridges are replaced and rinsed regularly.
- It’s design leaves something to be desired: it’s cheaply made using plastic, so it’s not as robust as it could be. The newer models will be at a better standard though.
- It takes cartridges, and the inserts are almost TOO unique. Replacing the inserts can be a bit of a hassle. Due to the unique shape of the filter cartridges, implementing your own media is difficult. For example, replacing the carbon cartridge with bio media isn’t easy.
- Hagen only produce 2 inserts for this filter; sponge (which is considered by them the bio and mechanical media) and carbon. They do not produce a specially tailored bio insert for the filter, and implementing an insert yourself will be difficult as the inserts for this filter are such a unique shape.
- The output is quite strong, but can be reduced depending on how you place the filter in the aquarium and whether or not you baffle it.
- We would consider this to only be a 2 stage filtration filter as there is no bio media insert and the carbon insert is difficult to replace. Although bacteria can grow in the sponge medium – this needs to be rinsed or replaced, which would affect the beneficial bacteria growth in the sponge.
We think this filtration is perfect if:
- You’re are keeping JUST a betta (and don’t have any other critters in the tank/if you don’t have an overstocked aquarium)
- You don’t have a planted aquarium – the carbon insert does a good job of keeping harmful chemicals at bay.
Aqueon QuietFlow Internal Filter Mini
As we know Bettas don’t like water disturbance, and a water current that breaks on the surface of the water can even cause them to surface for oxygen less frequently. This is one of the main factors that puts people off getting a filter for a betta, but the Aqueon is great for getting the water conditions just right. It’s one of the only internal mini-filters on the market with an adjustable output rate and position (check it out here on Amazon).
Being a mini-filter, and standing at about 7.8 inches, it does take cartridges, but it’s known for it’s easy adaptability. Shown in the image below, a user has added other manufactured inserts into the filter compartment – rather than having to stick to the Aqueon cartridges. As well as the easy adjustability of the filter media, the rate and direction of water flow on this filter can be adjusted. This is rare to find in mini-filters and is great for betta keeping as you can adjust the filter to create a comfortable current for your betta.
- Adjustable output height and output current. Can be easily positioned in the aquarium to create the most comfortable conditions for your betta.
- Easily interchangeable and modifiable.
- Sits internally, can be added to an aquarium with a fitted hood or lid.
- A good size – not too bulky.
- It is aimed at being a silent filter, hence the name ‘quietflow’ and is considerably more quiet compared to other filters on market. But after months of use, some users have commented that the components do start to make more noise, but nothing too unpleasant. If adjusted and positioned correctly, it tends to maintain its quietness.
- Comes with a bioscrubber insert.
- The filtration is easily modifiable.
- It does use a filtration cartridge, which needs to be replaced monthly, but the filtration compartment is basic in a good way – this means that filtration inserts (from other manufacturers) can be inserted independently.
- Can become noisy depending on the conditions in which the filter is used.
- As much as the return/output rate can be adjusted, some people have commented that it can still produce quite a strong current, which may or may not affect your betta (depending on the size of the aquarium and how you place it). It can be difficult to baffle, but placing sponge over the nozzle may beneficially reduce the outflow. See our guide on baffling here.