Filters For Fish Bowls: Type, Size, & Cost

People that enjoy using bowls for fish often prefer a minimalist approach when setting the system up. A simple desk or counter space over a stand, natural light over a hood, and so on. This keeps the system looking sleek and attractive; I get it!

But we don’t need to make compromises on the health of our pets in the name of simplicity! A basic filter for fish bowls offers a wealth of benefits and will pay for itself in disease and stress-free pets!

Do I Really Need a Filter for a Fish Bowl?

fish bowl filter

Absolutely! A good filter adds air to the system as well through increased circulation. Many of the filtration system designs for fish bowls are actually run using an air pump. These models can simultaneously filter the water for impurities and oxygenate the bowl at the same time!

Without a filter, you’ll see your water quality begin to fall within days after each water change. Ammonia, leftover food, and fish waste aren’t being properly processed in a filterless bowl. The water may even begin to stink and grow a thin sheen of decay-causing bacteria. Yuck!

What Fish Can Live Without a Filter?

I don’t really recommend keeping fish trapped in a bowl with no filter. Small filters are very inexpensive in most cases and provide a ton of benefits. These range from increased oxygenation thanks to surface agitation to their ability to break down waste and uneaten food.

But maybe your pet fish are subjected to power outages at times. Or you’re on a tight budget. In that case, you might try keeping a betta fish (Betta splendens). In the wild, bettas can be found in puddles, stagnant ponds, and other bodies of water where the conditions are poor: low dissolved oxygen and high levels of pollutants. These places are where their favorite food lives: insect larvae.

Bettas are so hardy because they have a labyrinth organ, a specialized set of structures that allow them to breathe air. Atmospheric air holds far more oxygen than even well-aerated water generated by an air pump. That said, we still should always strive to keep our pets in a healthy environment instead of being lax in cleanliness because they can tolerate it.

Betta Splenders Fish

Sponge Filters for Fish Tanks and Bowls

What’s most important when choosing a sponge filter for most people is selecting one that hits as many of the aquarium filter types as possible. To polish aquarium water, you need to provide mechanical, biological, and chemical water filtration. But if you’re missing one of these links, you can always perform water changes more often to compensate. Or keep your fish in a larger aquarium where the extra volume prevents things from getting too foul too quickly.

In a larger power filter, the cotton floss would normally keep the water clear. Sponge filters provide ample mechanical filtration by physically screening out small particles in the water column. Mechanical filters are the simplest form since they can’t act on free-floating problem molecules, but they are still essential!

Sponge filters also provide biological filtration by providing a home for beneficial nitrifying bacteria. See all of those miniature pores in your sponge? Billions of bacteria set up shop there, consuming ammonia and releasing nitrite. And a second set of bacteria eats that nitrite and converts it into nitrate.

Nitrate is the safest form of nitrogenous waste and is well tolerated by fish up to around 20-40 parts per million. That said, it’s still not great for their health at high levels. So you eventually need to remove nitrate in a timely manner through water changes. Plants will also consume nitrate as fertilizer!

Last but not least comes chemical filtration! The vast majority of fish tank and bowl filters use activated carbon (charcoal), which can bind to dissolved organic matter, preventing it from decaying into ammonia. This activated carbon needs to be replaced every couple of weeks; checking on it is always a good idea when performing water changes!

Sponge Filter Maintenance

Simple fish tank filters like sponge filters may not offer all the tricks and benefits of more advanced designs, like canister filters. But for small tanks (5 gallons and under), they do a fine job of keeping the water clean!

All that’s required is taking the time to detach the sponge from the air pump and squeeze it in a container of aquarium water. But there are two things to keep in mind: you should never clean a sponge filter in tap water. Remember those beneficial bacteria I mentioned earlier? The chlorine and chloramine in tap water is a disinfectant and therefore poisonous to them.

Second, don’t try and get the sponge completely sterile. Even if the sponge is completely clogged, we still want to preserve as much bacteria as possible. So get much of the gunk out but leave some behind so you don’t fully reset your aquarium cycle. When this happens, your filter loses its ability to provide proper biological filtration, which can lead to a sudden increase in ammonia levels.

Many filters for fish bowls also have chemical filtration included through activated carbon cartridges. Any activated carbon unit needs replacement during water changes – fortunately, it’s very inexpensive to purchase and quick to swap out!

Undergravel and Power Filters for Fish Bowls

I’m not a fan of adding an under gravel filter to a fishbowl or even a regular tank. These designs pull waste and excess food under the gravel, where it slowly decays. These decay products include ammonia and nitrite, and they aren’t prevented from simply recirculating back to your fish.

Power filters are another option to consider. They provide all three filtration modes: biological, mechanical, and chemical, and are very effective at oxygenating aquariums. Unfortunately, the majority are too strong for a small fish tank. The flow they output would simply blow your pet fish all over the place in a bowl or small tank! However, I managed to find a few sized perfectly for a bowl and included them above in the Recommended Fishbowl Filters section!

Recommended Fish Bowl Filters

Shopping for a fishbowl filter can feel overwhelming with so many options available for aquarists. So we’ve taken the time to curate this list of some of our favorite filtration options for a small fish tank or bowl! These are not only bestsellers but highly effective at providing circulation for tanks and bowls.

ImageLED Lighting AlternativesPowerPrice
Penn-Plax Smallworld Filter CartridgePenn-Plax Smallworld Filter Cartridge
  • Fits any drum or round fishbowl with 4 inch opening
  • Adjustable filter plate
  • Lift Tube included
  • Replacement filter cartridge
  • Air stone included
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AQQA Aquarium Internal FilterAQQA Aquarium Internal Filter
  • 【Powerful Filtering】Contains 3 filter media: Coarse media sponge can remove particles and debris; activated carbon can remove peculiar smell and discoloration in water; ceramic ball can remove toxic ammonia and nitrite. Delivers mechanical, chemical and biological aquarium filtration to maintain a healthy aquatic environment
  • 【Adjustable Flow Valve】This aquarium filter equipped with an adjustable flow regulator, that you can distributes gentle water flow to make it is safe for delicate fish or shrimp; or you can creat a beautiful waterfall with rock in the fish tank; Or you can set the maximum flow rate to achieve the best dissolved oxygen content to promote healthier and more active fish. Suitable water flow, fit for fish bowl and grass cylinder,so it satisfy your various demand
  • 【3 in 1 Multi-function aquarium filter】This filter come with 2 kinds of water outlet and an air tube, you can switch increase oxygen and filtration, wave maker pump function easily. The transparent filter box is visible that you will know when to clean or replace the filter cartridge
  • 【Ultra-Quiet】Ultra-quiet motor and internal pump design helps dampen noise and eliminate leaks with self-priming feature, more quiet than external filter. It's multiple noise reduction designs offers you and your fish a quiet and comfortable night
  • 【Fit】 Available in 79 GPH, 120 GPH, 172 GPH sizes. The 79 GPH aquarium filter is for 5-10 gallon fish tank, the 120 GPH is for 10-20 gallon fish tank, and the 172 GPH is for 15-30 gallon fish tank.
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XEOGUIYA Mini Fish Tank FilterXEOGUIYA Mini Fish Tank Filter
  • 3 layers of filtered: funnel air outlet, air stone filtration and filter sponges. Multiple filtration, the effect is better, forming a good aquarium environment.
  • The application scope of the mini filter: spherical fish tank, small fish tank and other special-shaped small fish tank. The small water flow can ensure excellent water quality. Help your little fish or shrimp live a happy and healthy life.
  • Filter size: 9.8x3cm. This sponge filter has an ultra-small size and a small footprint, making it ideal for use in 1-10 gallon fish tank bowls.
  • Tips: This filter must be used with an oxygen pump. At the same time, please be careful not to use an oversized air pump to avoid uneven mixing of water and air. (NO INCLUDE Air Pump)
  • You can get: 1 x filter. Easy to install and remove. It is recommended to clean the small sponge regularly, just use the aquarium water to rinse or squeeze the sponge.
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AQUANEAT Mini Sponge FilterAQUANEAT Mini Sponge Filter
  • This sponge filter is super mini size, takes up a little room, perfect for use in 0.5-3 gallon fish tank
  • Dimension:1.5”D X3”H
  • Safe for fish: soft sponge material, traps floating debris and won't suck up your fish
  • Easy to set up & clean: simply install an airline into the unit and turn on the air pump, simply rinse and squeeze sponge in tank water
  • Package includes: 1 mini sponge filter ,40 inch airline tubing ,1 control valve
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Zyyini Mini Aquarium FilterZyyini Mini Aquarium Filter
  • 【ULTRA-THIN DESIGN】 Ultra-thin design, save space inside the aquarium bowl, more beautiful.Comes with filter sponge, bio balls, air stone inside, keep your fish bowl clear and clean.The air stone release air bubbles smaller, denser, more uniform,help fish swim happily in aquarium,fish tank,koi pond.
  • 【EASY TO USE】 simply install an airline into the unit and turn on the air pump, great way to clean and oxygenate your bowls.It's easy to use simply place it anywhere at the bottom of aquarium.
  • 【EASY TO CLEAN】 simply squeeze the sponges in bowl water.simply place it anywhere at the bottom of aquarium.Air stone is heavy enough to stay at the bottom and the air stone does not float up.
  • 【WORKS QUIET】 This aquarium bubbler will diffuse air into the tank in a gradual manner and pushes tons of oxygen.quieter than other types with large bubbles tends to cover the noise from the air pump.
  • 【SUITABLE FOR】 Suitable for shrimp bowl, betta bowl, breeder bowl, goldfish, discus, guppies, fry, baby fish or other fish.
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Using Plants to Filter Fish Waste

Buying air or electric-driven filters is very popular for fish tanks. But what if I told you that you could make your very own biological filtration system for a tank or bowl?

There are aquariums designed to use live plants as a source of filtration! Heavy plant growth can replace a filter entirely because plants use ammonia, nitrite, and nitrate as a source of food. To fish, these are harmful chemicals. But for plants, they are an important source of nitrogen!

Plants also consume the carbon dioxide (CO2) released by fish, releasing oxygen in exchange, which all animals need for survival. And considering how little water circulation and filtration that most bowls have, extra oxygen is always useful!

clean water

There is a wide variety of plants that can be kept in a small tank or bowl. So long as you have enough light to help them grow, that is. Just don’t rely on the plants to provide food for the fish, as many goldfish and betta bowls with spider lilies advertise. They suck up excess nitrogen and add some oxygen. But you’ll still need to feed your fish and perform regular water changes as normal.

Anacharis (Egeria densa) is a favorite for many fish bowl keepers. It is a vibrant green plant with soft leaves that enjoys ample light but is otherwise easy to grow. Another is Hornwort (Ceratophyllum sp.).

The more light you have, the more your options open up. One advantage that fish bowls have over a tank is that they are usually much shallower. This means that it’s easier to get bright light all the way down to the bottom, where carpeting plants grow.

Wrapping Things Up

tank water

New aquarists often buy fish bowls for their simplicity and beauty. While they can be small and simple, I still recommend having a filter in a bowl. Fish create waste like any other animal, and those agents need to be cleaned up to avoid stress and disease. Filters also circulate the water, providing oxygen and preventing the water from becoming stagnant and smelly.

If you have an aversion to using any more technology in your fish bowl, then consider adding live plants instead! Once established, they do everything that a standard filter does while providing an extra dose of beauty to the environment. They do need ample lighting – but a bowl is shallow enough for even a small light to be enough. And if you have a nearby window, then natural light can also keep your plants thriving and, by extension, your fish healthy!

Kelly Stanley