Looking for the best filter for your betta fish tank? In this guide, you’ll be walked through how to select the filter that’s best for your setup.
You’ll learn how to choose one, the different options available and my favorite products for each category.
By the end, you’ll know exactly what you need.
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Product Table for Betta Fish Filters
Do Betta Fish Need a Filter?
The short answer is yes, betta fish do need a filter.
Betta fish need clean water to live well in their tank, just like any other fish you might keep. Poor water conditions can lead your betta fish to succumb to disease or to suffer from issues like fin deterioration.
A filter goes a long way towards preventing the buildup of harmful microorganisms and organic detritus from uneaten food and fish waste. Cycling the water in the tank through the filter also helps to oxygenate the water, which can lead to overall healthier conditions in the tank for your betta.
Just as important, a filter drastically reduces the amount of work you need to do to keep the tank clean – which means you’re more likely to keep up with tank maintenance. For tanks with a filter, you only need to replace about 30% of the water and vacuum the gravel each week.
All of that takes just a few minutes of work compared to a betta tank without a filter. While a tank without a filter can work, you need to change out all the water each week and thoroughly clean all of the decorations in the tank.
That means a lot of distilled water, a lot of cleaning time, and a lot of stress for your betta as you transfer it to a holding tank while you clean out the aquarium.
For all these reasons, it’s well worth investing in a filter for your betta fish.
What to Consider When Choosing Your Betta's Filter
There are a number of different types of filters available, all of them with different characteristics.
So what filter features matter for your betta fish? Here, we’ll highlight the most important things to watch out for when choosing a filter.
Betta fish do best with a filter that has a low flow power. Otherwise, they tend to get knocked around by the currents created by a high-powered filter – and that can cause stress.
Ways to Reduce Flow If Your Filter is Too Powerful
If you find out that your filter is too powerful for your betta fish, there are some things you can try to reduce the flow.
First, if you have an adjustable filter, you can simply adjust the flow rate. This is the simplest solution, but you’ll still be limited by the minimum flow rate on your filtration system.
If adjusting the flow on the filter isn’t an option, you can limit the water intake. The best thing to use for this is a pair of pantyhose, which can be cut to fit over the filter intake and slow down the rate of water entering the filter.
Short of cutting the flow, you can disperse it with a baffle. A baffle is anything that works to block and slow down the water from the filter outlet.
Common baffles include mesh tank screens and inexpensive kitchen sponge holders that can be suction-cupped to the side of the tank.
Finally, you can help your betta hide from any excessive flow coming from your filter by placing decorative plants, logs, and other items throughout the tank.
These decorations effectively give your betta plenty of places to rest without having to worry about the water current from the filter.
How Big is Your Betta's Tank?
The flow rate you need in a filter also depends on the size of your betta tank.
Your filter should cycle through all of the water in the tank four times per hour. So, to figure out the minimum flow rate you need, in gallons per hour, multiply the size of your tank in gallons by four.
However, remember that this number is just a base calculation that indicates the flow rate needed when there is nothing in the tank. If your betta tank is filled with decorations, you will need a slightly more powerful filter than that calculation suggests.
Finally, keep in mind that using multiple smaller filters is better than opting for one large filter. Using multiple filters will minimize the current that your betta has to fight against and improve the overall filtration of the tank.
There are three stages to filtration in an aquarium: mechanical, biological, and chemical.
Mechanical filtration is the first step of filtration, in which any particles floating in the water are removed. Ceramic cylinders, coarse sponges, and filter floss are all common media for mechanical filtration.
The biological stage of filtration incorporates beneficial bacteria that remove organic matter – like uneaten food and fish waste – from the tank water.
The biological filtration portion of the filter typically includes media that is friendly for bacteria to grow on, such as Bio-balls or porous ceramic cartridges.
Chemical filtration is designed to re-balance the chemistry of the water and to remove any chemical impurities that are dissolved in the water. The most common chemical filter medium is carbon, since it has a short one-month life.
7 More Tips on Choosing Your Betta Fish Filter
1. Keep the output current low or disperse the outflow from the filter as much as possible. This will reduce the amount of fighting against the current that your betta will need to do.
2. Look for a filter with a cartridge system that makes it easy to remove and replace any of the mechanical, biological, or chemical stages of the filter. This makes maintaining the filter much simpler and faster, and allows you to change out just the part of the filter that needs replacing.
3. Make sure that the filter you choose has the flow rate and mechanical, biological, and chemical filtration stages needed to keep your aquarium clean.
Remember that the flow rate you need may be higher depending on how much stuff is in your tank. In addition, some natural decorations like driftwood can leach impurities into the water that may require special chemical filtration.
4. Consider the filter media – does it have mechanical, biological, and chemical media, or just two of the three? What media you need depends on what else is living in your tank besides your betta, so we’ll cover this more below.
5. Think about reliability. You need a filter that is likely to work over the long-run without clogging or breaking down frequently. Taking other people’s experience with a specific filter into account can go a long way towards saving you from dealing with a poorly made filter.
6. Look for a filter with an adjustable output. Having the ability to adjust your filter’s output makes it much easier to lower the flow rate if your betta is stressed by the current in the tank.
7. Consider whether a filter matches your tank’s aesthetics. While any filter still needs to be practical in all other regards, it doesn’t hurt to have it blend in with your tank decoration.
Popular Types of Filters Available for Betta Fish Reviewed
Now that you know what to look for in a filter for your betta fish tank, let’s look at some of the most popular types of filters for betta fish. We’ll also highlight our favorite model of each type of filter.
1. Canister Filters
Canister filters are a high-throughput filtration option for betta tanks of nearly any size.
This type of filter actually pumps water out of the tank, through a pressurized canister, and back to the tank via a spillway or spray bar.
This allows canister filters to boast high water flow rates. They also don’t distract from the aesthetic of the tank since they are hidden behind or underneath the aquarium and are very quiet.
The most important advantage to canister filters is that you can customize the media that is inside them to suit your tank’s needs. They are also easy to open up for cleaning and replacing media.
However, the high flow rates of canister filters aren’t always a good thing for betta fish, especially since the outflow is pressurized. Especially in smaller tanks, this pressurized flow can create stressful currents for your fish.
Best Canister Filter for Your Betta Reviewed: Fluval External Filter 206
This canister filter is designed to handle tanks up to 45 gallons in volume and features all three of mechanical, biological, and chemical filtration stages.
Fluval sells a wide range of media so you can customize the filtration process to match your betta’s needs as closely as possible. Plus, the chemical and biological stages use separate media so they can be changed out independently of one another.
The canister is designed with a sound-dampening impeller so you’ll barely know it’s there when you’re not changing out the media. Plus, the intake strainer and dual layer foam screen are designed to drastically reduce the incidence of clogs.
While the outflow is somewhat powerful for a betta fish and will likely require you to install a baffle, the pressurized flow also does an excellent job of aerating your aquarium.
2. Sponge Filters
Sponge filters function by sucking water through a porous sponge material, which serves to provide both mechanical and biological filtration. The biological filtration is highly effective because helpful bacteria are able to colonize the porous spaces of the sponge.
One of the major advantages to sponge filters for a betta tank is that the suction through the filter is created by an air stone rather than a pressurized pump. That leads to relatively gentle water outflows, which are ideal for betta fish.
In addition, sponge filters tend to be one of the least expensive filtration options and don’t require much maintenance.
The main downside to sponge filters is that they are large and not aesthetically pleasing. Most people who use sponge filters opt to hide them behind decorative kelp, in the rear of the tank.
In addition, sponge filters do not provide chemical filtration. However, it is possible to add a carbon filter to the outflow of a sponge filter if needed.
Best Sponge Filter for Your Betta Reviewed: Xinyou XY-2831 Sponge Filter
This inexpensive sponge filter from Xinyou is designed to provide mechanical and biological filtration for a tank that is 10-20 gallons in size.
While the filter does not come with an air stone, it is easy to outfit with a small stone to create a highly efficient suction system that won’t stress out your betta fish.
The filter is extremely simple in design and can be used as a pre-filter or as a standalone filter. The sponge material works well as a home for beneficial bacteria, as evidenced by the attraction of shrimp towards this filtration device.
The only real downside to this filter is that it is not pretty – the black, mechanical-looking design is certain to be out of place with any tank aesthetic, so you’ll want to hide it behind some other decorations.
3. HOB Filters
HOB – hang-on-back – filters are designed to suck water out of the aquarium and through a filter that offers mechanical, biological, and chemical filtration.
Since they are behind the tank, HOB filters are easy to access for maintaining the media and don’t detract from your tank’s available space or aesthetic.
HOB filters typically offer more effective mechanical filtration than sponge filters. However, many aquarists recommend using a sponge filter as a pre-filter to HOB filters since they offer better biological filtration.
Using a sponge pre-filter also protects your betta fish from the relatively strong inflow rates of HOB filters.
In addition, HOB filters often have outflow rates that can be distressing to betta fish. Thus, when choosing a HOB filter, it is important to look for one that has an adjustable flow rate.
Best HOB Filter for Your Betta Reviewed: AquaClear Power Filter
This HOB filter from AquaClear offers a number of advantages for betta fish, the most important of which is a re-filtration system that allows you to control the outflow rate.
At slower flow rates, up to half the water in the filter is processed multiple times, which also gives this filter some of the most impressive water contact times of any filter on the market.
The filter comes with AquaClear foam as a mechanical filtration media, activated carbon for chemical filtration, and BioMax and Cycle Guard for biological filtration.
The relatively large size of the filter allows it to contain large volumes of media, and the media is straightforward to customize to better meet your betta’s needs.
While this model is designed for tanks up to 20 gallons, AquaClear offers the same HOB filter in multiple sizes to fit tanks of any volume.
4. Undergravel Filters
An undergravel filter is a set of plates that sits underneath the gravel media at the bottom of your aquarium and sucks water through the gravel before recirculating it to the top of the tank.
This type of filter provides effective mechanical and biological filtration as water travels through the gravel, and some models provide chemical filtration modules in the outflow tubing.
Importantly, since this type of filter traps debris inside the gravel within the tank, it is extremely important to use a gravel vacuum on your tank frequently to keep the tank clean and maintain the chemistry of the water.
In addition, while undergravel filters distribute the water inflow across the base of the tank, reducing currents in that direction, the outflow can be quite strong. Depending on the design of the filter, this may be a problem for your betta or the water may be directed all the way to the water’s surface.
Best Undergravel Filter for Your Betta Reviewed: Lee’s 40/55 Premium Undergravel Filter
This inexpensive undergravel filter from Lee’s is an ideal choice for betta fish because it uses a single plate that distributes the inflow current across the entire base of the tank.
In addition, the siphons are designed to output water all the way to the tank’s surface so that the impact of the outflow current on your betta fish is as minimal as possible.
In addition to filtering water through the gravel, this undergravel filter includes activated carbon add-ons that can be attached to the outflow tubing.
Another advantage to this filter is that the plastic bedding itself is quite durable compared to other undergravel filters. As a result, you won’t need to remove the filter from your tank during the life of your betta fish.
5. Corner Filters
Corner filters are one of the oldest, tried-and-true types of filters out there. These filters are designed for tanks up to 25 gallons in size and typically sit in the rear corner of the tank.
They function by using an air stone to push water through the filter, which contains a variety of media to mediate mechanical, biological, and chemical filtration.
There are several advantages to corner filters. First, they can be filled with a custom media mix to perfectly match the needs of your betta fish.
Second, they use an air stone to bubble water through the filter, which does not create much current that could disturb your betta fish. Finally, corner filters are one of the least expensive filtration options available.
The only downside to corner filters is that they can make it more difficult and time-consuming to change out the media than canister or HOB filters.
Best Corner Filter for Your Betta Reviewed: Jardin Aquarium Corner Filter
This small corner filter from Jardin is ideal for small betta tanks that are too heavily disturbed by other types of filters. The filter is as simple as it gets, with just a single chamber that can be opened from the top to allow you to add in custom filtration media.
The outflow tubing can be pulled apart to augment how water is outflowed – whether straight up or across the back of the tank. With a small air stone, this filter will not cause excessive currents even in a small 5-10-gallon betta tank.
6. Internal Power Filters
Internal power filters are designed to sit inside your tank and flow water through a variety of filtration media types. The primary advantage to internal power filters is that the outflow can often be turned in any direction and adjusted using an internal flow meter.
The main downside to internal power filters is that unlike other filter types, you will not have as much control over the composition of the filtration media.
While that may not be an issue for tanks that are typically clean with just any filtration, for aquariums that have issues with water chemistry or disease outbreaks you may want more customization of your filtration system.
Best Internal Power Filter for Your Betta Reviewed: Koller Products TOM
This small and versatile filter from Koller Products is designed specifically for small betta tanks less than 10 gallons in volume.
The outflow is distributed across a set of 10 nozzles to reduce the current that your betta fish feels, and the filter can be pointed in any direction within the tank to further minimize its impact on your fish.
Even better, the flow rate of the filter can be easily adjusted to account for the size of your tank.
The filtration media inside the tank is dense foam with activated carbon, which provides a measure of all three stages of filtration.
While the media volume is relatively small, this is not an issue for small tanks and the media does not need to be replaced more than once every several months.
Which Filter is Best for Your Betta?
Which filter is best for your betta depends on a number of factors, including the size of your tank, which filtration stages you need, and your budget.
The most important things when choosing a filtration system are that it has the right media to keep your water clean of harmful bacteria and debris that could alter the water chemistry, and that the filter itself does not create a current that could stress out your betta fish.
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Last update on 2019-02-19 / Affiliate links / Images from Amazon Product Advertising API