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Fish Tank Filter Blowing Bubbles: 7 Common Reasons & Solutions

Brooke Billingsley

By Brooke Billingsley

aquarium filter nozzle with bubbles

If you have an aquarium that contains anything other than a couple of shrimps, then you probably have some type of filtration system. Aquarium filters come in many varieties, with hang-on-back, canister, internal, and sponge filters being the most common.

Regardless of the type of filter you have, there are lots of issues you can experience with your filter, from power outages to clogs. One thing that you may notice with your filter is that it seems to be releasing an excessive number of bubbles into your tank. While bubbles won’t hurt your tank, there are a few reasons that your filter may be bubbling.

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The 7 Reasons That Your Tank Is Blowing Bubbles

1. It’s Hooked Up to a Pump

This might seem obvious to some, but many people are not well-versed in how their aquarium filter functions. Some filtration units require you to connect an air pump to create bubbles and increase oxygen exchange in the water. If you’re unfamiliar with how your filter works, though, then you may not have realized that the purpose of the air pump is to create bubbles, not to power the filter itself. This type of setup is a really fantastic way to increase the amount of available oxygen in the water for your tank livestock to use.

MODERN FISH TANK
Image Credit: Frantisek Czanner, Shutterstock

2. It’s Dirty

When was the last time you took your filter apart and cleaned all of the components? For most of us, it’s probably been a while—maybe never. While it’s not necessary to do it frequently, you should clean all of the components of your filter from time to time to maintain optimal functioning. If there’s livestock in your tank, then there’s definitely protein in the water from food, waste, and plant matter. Protein stuck within your filtration system can lead to excessive bubbling.

If you do take your filter apart to clean the whole thing, make sure to set your filter media aside in a bowl of dirty tank water. If you replace or clean your filter media and your filtration system, then you are risking crashing your tank’s nitrogen cycle, which can lead to injury, illness, and death for your fish.


3. It’s Clogged

There are a number of things that can get into your filtration system. While it can be annoying to deal with a clogged filter, this means that your filtration system is doing its job and pulling in waste from the water. Over time, fine particulates can lead to clogs in your filter, but you’re more likely to see clogs from collections of things like dead plant matter, fish waste, leftover food, and algae. To maintain your tank’s nitrogen cycle, try to minimize how frequently you change your filter media, opting instead for cleaning it and reusing it until it is no longer viable.

colorful fish in tank with bubbles
Image: xzgorik, Shutterstock

4. There’s Excess Protein in the Water

While we already discussed how protein stuck in your filtration system can lead to excessive bubbling, there are some situations in which the protein levels in your aquarium can get excessively high. When this happens, no amount of filter cleaning will fix the problem because the protein levels in the water will continue to lead to bubbling.

This isn’t a common issue in freshwater tanks, but saltwater tanks are prone to high protein levels. The addition of a protein skimmer to your tank can help to reduce the protein levels in your water. You should also consider causes of excess protein in the water, like overstocking and overfeeding.


5. There’s Soap in the Filter or Water

When you clean any part of your tank or filter, it’s important that you avoid the use of soaps and cleaning chemicals. Stick to water, although hydrogen peroxide, white vinegar, and bleach can all be useful for very specific cleaning purposes in the aquarium world.

Soaps have a tendency to stick around, no matter how well you rinse. It’s very easy to get soap into your tank by cleaning your filter with soap. It’s also not uncommon for people to stick their hands into their tank with soap still on them from washing, which can lead to a collection of soap in the tank over time. We’ve all seen that when soap is exposed to running water, it creates bubbles.

fish tank with filter hose
Image Credit: RaKav007, Shutterstock

6. Strong Water Flow

Have you ever watched a waterfall? You probably noticed that bubbles were coming up around the water where the waterfall stream broke in. In the case of strong waterfalls, you may have even seen bubbly foam collecting in the area. Strong and aggressive water flow can lead to bubbling in your tank.

The easiest solution is to reduce the strength of your filter’s water flow. If this isn’t possible due to the needs of your tank livestock, then you may need to use things like baffles to alter the water flow, so the bubbles are less noticeable.


7. It Has Broken Parts

Even if you take your filter apart and keep all of the components clean as a whistle, parts on your filter will start to give out at some point. It’s completely normal and expected for parts to begin to fail on any type of mechanical device with constant use. Broken parts can lead to improper functioning of the filter, which may lead to bubbling.

Replacement parts are available through many vendors, so it is often possible to replace broken parts instead of the entire filtration system. However, it may eventually become necessary to simply replace the whole system.

fish tank filter hose
Image Credit: mariait, Shutterstock

In Conclusion

There is no harm in extra bubbles being present in your tank. In fact, they can actually increase the amount of oxygen in the water and improve the health of your tank livestock, which is why things like air stones and sponge filters are so popular. Although bubbles aren’t harmful, they can indicate that there’s a problem with your filter or water quality. If you notice a change in your filter’s functionality or an increase in bubbling in the tank, then it’s a good idea to check out possible causes to maintain the health of your tank.


Featured Image Credit: Lapis2380, Shutterstock

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