Best Small Aquarium Filter – Top 5 Reviews, Tests, Guide, FAQs & More

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It’s difficult not to agree with us when we say that when you have a small aquarium, buying a filter that’s appropriately suited for it can be quite difficult. 

That’s why we decided to round up every effective filter which is suited to perform well in a small aquarium setting in the form of this comprehensive list. 

In today’s post, we’ll discuss the intricacies of small aquarium filters and the extra care you have to take when you’re working with a filter in a smaller setting.

Top Pick

Coming with a small and unobtrusive design, this product doesn’t take up too much space in your aquarium and is wonderful for beginners.

Runner Up

This product comes with a spray bar that allows you to alter flow and direction. It provides quiet filtration which is great for all kinds of small aquariums.

Also Great

This filter is incredibly easy to set up and clean. It makes no noise and you’ll find you don’t have to worry about your small fish getting swept into it.

After rigorous testing, we’ve found these three filters to be the best ones among the crowd. 

Now, let’s get into the detailed reviews for the top 5 best small aquarium filters. 

Best Small Aquarium Filter - Top 5 Reviews

1. All-Around Best Small Aquarium Filter - AZOO Aquarium Mignon Filter Review

This product was an incredibly pleasant surprise since its small size had all of us convinced that it wouldn’t perform quite adequately. It very quickly proved all of us wrong as it was able to make the water in our 3-gallon tank absolutely clear at an extremely rapid rate. 

Its small size is great because it allows you to have so much room in your aquarium for your fish to swim in. The pre-filters that come with it are also a very welcome addition as you can attach them to your filter to ensure your fish and fish fry don’t get sucked into the filter. 

Features of AZOO Aquarium Mignon Filter – Best Small Aquarium Filter

  1. Dimensions: 3.2 inches by 3.8 inches by 6 inches
  2. Weight: 1.6 ounces
  3. Adjustable flow control knob
  4. Appropriate for aquariums up to 10 gallons
  5. Comes with a pre-filter
  • Easy to clean
  • Affordable
  • Beginner-friendly
  • Incredibly quiet
  • Small in size
  • Pre-filter sponges are of a very quality

If you have a small aquarium that is housing small fish or fish fry, then this filter is perfect for you. It uses very little electricity and does not let your fish get swept up into it.

2. Best Underwater Small Aquarium Filter - Penn Plax Cascade 300 Submersible Aquarium Filter Review

This product is fully submersible and thus, provides you with a number of options as to where you want to position this filter inside your aquarium. This coupled with the fact that it’s a relatively small filter means that your fish will have ample room to swim inside your small aquarium. 

Its powerful flow rate enables it to adequately filter aquariums up to 10 gallons and if you have an aquarium that is smaller than that, you can lower the flow rate easily using the adjustable flow control knob. It even comes with a spray bar that you can use to adjust the direction in which the water is streaming into the aquarium.

Features of Penn Plax Cascade 300 Submersible Aquarium Filter

  1. Dimensions: 5 inches by 2 inches by 3 inches
  2. Weight: 1.4 ounces
  3. Maximum flow rate of 70 gallons per hour
  4. Appropriate for aquariums between 1.5 gallons and 10 gallons
  5. Adjustable flow rate and flow direction
  • Very small footprint inside aquarium
  • Low energy consumption
  • Easy installation
  • Extremely lightweight
  • Excellent build quality
  • Can get loud with use over time

If you want a filter that’s easy to position and place inside your aquarium, this is the product you’re looking for. It’s highly durable and very effective.

3. Best Affordable Small Aquarium Filter - Huijukon Double Super Biochemical Sponge Filter Review

A biochemical sponge filter is definitely a great option for you if you’re running a small freshwater aquarium that contains only fish. Biological and mechanical filtration are absolute necessities when it comes to the successful running of an aquarium but chemical filtration is not as important and can be substituted using water conditioning agents. 

This filter works by having an air pump attached which circulates water onto it where the sponges catch all the dirt, gunk and debris. These same sponges are the spot where beneficial nitrifying bacteria grow as well. 

Features of Huijukon Double Super Biochemical Sponge Filter 

  1. Dimensions: 5.5 inches by 4.1 inches by 0.9 inches
  2. Weight: 2.08 ounces
  3. Comes with an air pump
  4. Suction-cup mounting
  5. Double 7-layered sponges
  • Inexpensive
  • Easy to clean
  • No danger of fish getting swept up into it
  • Lightweight
  • Extremely small in size
  • Does not perform chemical filtration 
  • Air pump that comes with it is loud

If you’re looking for a small aquarium filter that provides the biggest bang for your buck then this product is ideal for you. It’s incredibly user-friendly and it makes a lot of sense to have this kind of filter in a small aquarium.

4. Best Quiet Small Aquarium Filter - Whisper In-Tank Filter Review

You’ll be able to deduce from this product’s name that it is incredibly quiet and we were definitely blown away by this quality of it. Oftentimes, you feel like it’s not even turned on because of how quietly it operates. 

Apart from it being quiet, it’s also incredibly effective and is able to quickly clean up an aquarium consistently within a very reasonable time. 

It’s also specifically designed to utilize energy as efficiently as possible so your electricity bill does not get driven up by ridiculous amounts. 

Features of Whisper In-Tank Filter

  1. Dimensions: 3 inches by 3 inches by 7.4 inches
  2. Weight: 8.8 ounces
  3. Filter flow rate: 27 gallons per hour
  4. Appropriate for aquariums up to 4 gallons
  5. Comes with a bio-scrubber
  • Requires little maintenance
  • Budget-friendly
  • Easy to use
  • Small in size
  • Extremely silent
  • Quite heavy for a small aquarium filter

If you’re frustrated by how much noise many small aquarium filters make then this product was definitely made for you. It’s very silent and you’ll find that it doesn’t take too much effort to maintain either.

5. Best Small Aquarium Filter with LED Cleaning Indicator - Aqueon QuietFlow LED PRO Aquarium Power Filter Review

We’re always excited to test out products by Aqueon and products like these are the reason why. This product comes with a durable body that is able to filter most small aquariums highly efficiently. 

The self-priming feature is a welcome one as you don’t have to prime it yourself when you first set it up or after cleaning sessions. All you have to do is mount it and turn it on, it will do the rest for you. 

Features of Aqueon QuietFlow LED PRO Aquarium Power Filter

  1. Dimensions: 6.4 inches by 6.3 inches by 3.8 inches
  2. Weight: 1.2 pounds
  3. Maximum flow rate of 100 gallons per hour
  4. Self-priming mechanism
  5. LED indicator for when it needs cleaning
  • Highly effective
  • Doesn’t take up too much space
  • Comes with a lifetime warranty
  • Affordable
  • Extremely easy to set up
  • Can be difficult to handle due to its heavy weight

If you forget or don’t have the time to check every time whether your filter needs cleaning or not then this is the product you’re looking for. It does this job for you and its self-primer means it’s extremely easy to install.

best small aquarium filter

Buyers’ Guide 

How do I know what size of a filter is appropriate for my aquarium? 

The main way in which you can estimate how powerful of a filter you need for your aquarium is through observing the flow rate. 

When it comes to observing the flow rate, you generally want a filter that is able to circulate all the water inside your tank at least four times in an hour. This means that your flow rate should be four times that of your aquarium size. For example, if your aquarium is 10 gallons then your filter’s flow rate should be at least 40 gallons per hour for it to be adequate. 

Can I skip getting a filter if my aquarium is small enough?

This is a common misconception among beginner aquarists as well as some advanced aquarists too. The truth is that no matter how small of an aquarium you have, if you have a living being inside it, it’s going to produce waste that will need to be cleaned up. You could make the argument that you can take care of this by cleaning your aquarium regularly but a small aquarium gets dirty very quickly and the number of times you would need to clean your aquarium day-to-day would just become too time-consuming and frustrating. You would be much better off just getting a filter for your aquarium. 

Not to mention, water conditions such as temperature are also quite difficult to control in a smaller aquarium. Having a filter that’s constantly circulating water can help immensely in that regard.  

What are some things to consider when buying a small aquarium filter?

Here are some things to consider when buying a small aquarium filter which can help you narrow down your search for the appropriate one: 

  • Aquarium Size and Flow Rate

We’ve discussed this earlier about how you can calculate the appropriate flow rate of your filter by observing your aquarium’s size.

  • Physical Size of your Filter 

While this is important in all aquariums, it is especially important when buying a filter for a small aquarium. A small aquarium already has very little room for fish to swim in so you have to treat the amount of space your fish have as a valuable asset. You don’t want to invest in a filter that is extremely large in size and takes up a lot of space inside your aquarium. This will be unhealthy for your fish and will also just look plain ugly. Search long and hard for a filter that has a small footprint and doesn’t take up a lot of space inside your tank. 

  • Price 

Most small aquarium filters are generally cheap due to their low power and small size. However, there do exist some manufacturers that sell filters at ridiculous prices just because they’ve added little gimmicks into their products which you really don’t need. When you’re running a small aquarium, you don’t really need a filter with a lot of extra features. Most of the time, all you really need is a standard filter that can perform all three types of filtration. In fact, sometimes you can even get away with a filter that can only perform biological and mechanical filtration. Be sure to identify what your small aquarium really needs and avoid spending extra dollars on a filter that has extra features that you’ll rarely ever use. 

How do I install a small aquarium filter? 

Here are some general steps to setting up your filter in your small aquarium: 

  • Completely assemble your filter before mounting it onto your aquarium (unless the instruction manual says otherwise). 
  • Once it’s fully assembled, mount onto your aquarium wall using whatever mechanism the manufacturer has provided with the filter such as suction cups, etc. 
  • Fill the filter with water until it is spilling over into your tank. Note that this water should have been treated in the same way as the water in your aquarium, i.e., dechlorinated and treated with a water conditioning agent. 
  • Next, check to see if all tubing and wires are properly connected and turn it on. Let the filter run in your empty aquarium for a few weeks. This process is essential in order to build beneficial nitrifying bacteria inside your tank. You can add your fish once the ammonia levels inside your small aquarium go down to zero. 

What are some tips for keeping a small aquarium filter clean? 

The most effective way to keep your small aquarium filter clean is to be wary of how much food you’re giving to your fish. Excessive amounts of food can easily get swept up into your filter where it will eventually end up clogging it. 

Another great way is to baffle your small aquarium filter. This refers to partially blocking the inlet pipe with a permeable substance such as a sponge. This sponge will filter out a lot of the gunk and waste before the water even reaches the inside of your filter. Note that you should ensure you’re not lowering your filter’s flow rate too much when you do this.

Frequently Asked Questions

How long can fish survive without a filter? 

Technically, the beneficial nitrifying bacteria start dying out within 30 minutes of your aquarium filter turning off. Most fish are able to survive in an aquarium without a filter for about 24 hours but if you have a smaller aquarium, you may have a much smaller time window. We recommend not letting your fish go without a filter for any more than 6 hours if you have a small aquarium. 

What should I do if my small aquarium filter stops working? 

Well, the most obvious thing to do would be to see what’s wrong and try to get your filter to start working again. The most common culprit is often something clogging or impeding the impeller from working properly. If you can’t get your small aquarium filter to work, we recommend going out and buying a replacement as soon as possible. During the time when you don’t have a functioning filter inside your small aquarium, you can keep the water clean by performing regular water changes. 

My fish are having trouble swimming properly after I’ve installed my small aquarium filter. Why is this? 

This is often a sign that your aquarium filter is too strong; it’s creating currents that are too difficult for your small fish to swim in and they are having trouble going in the direction in which they want to go. You can solve this by lowering the flow rate in your filter if it has that option or getting a lower-powered filter. 

My fish seem to be developing skin-related diseases after I’ve installed my small aquarium filter. What could be causing this? 

This may definitely be because you have not cycled your aquarium properly and there is still a lot of ammonia present in your aquarium which is causing your fish to become stressed. It’s very likely that a fish fluke outbreak has occurred inside your tank. Fish flukes are a group of parasites that attack fish skin and gills and they are often caused due to stress in fish due to poor water quality. 

Can my small aquarium filter fix algae problems in my fish tank? 

No. A small aquarium filter is not equipped to deal with an algae problem inside a small aquarium. If you want to remove algae from your aquarium, you’re going to have to look to other methods such as keeping your tank in the dark for a couple of days, introducing algae-eating fish or installing a UV sterilizer. 

What are the most appropriate types of filters for smaller aquariums? 

You don’t quite often see canister filters in smaller tanks since they are normally made for aquariums of larger sizes. The types of filters most commonly found that are made for smaller aquariums are usually HOB filters, power filters, and fully submersible filters. Sponge filters can also be a great option for smaller aquariums and while they’ve gone out of style over the last few years, under-gravel filters used to be an option too. 

What’s the most appropriate place on an aquarium to mount my small aquarium filter? 

That depends on what type of filter you have. 

If you have an external filter, it’ll be placed somewhere between your tank and the power socket so you’ll probably have to hide it externally such as in your aquarium table cabinet. 

HOB (Hang-On Back) filters, as the name suggests, hang onto the back of your aquarium. You should normally hang these in one corner so they take up minimal space. 

What are some advantages of pre-filters? 

The main advantage of installing a pre-filter or pre-filters into your aquarium is that it provides a great breeding ground for the production of beneficial nitrifying bacteria. You’ll find that an aquarium that has a pre-filter installed into it cycles much more quickly than an aquarium without one. 

What is normally considered a small aquarium? 

There are no clear-cut definitions but most aquarists agree that a small aquarium is anything below 20 gallons. 

How often should I change my filter media?

This depends on a number of factors such as your aquarium size, filter flow rate, how many inhabitants there are in your tank and what you feed them. Generally, you should check your filter media every other week to see if it needs changing. Different types of filtration media require changing at different intervals. 

Final Verdict

With small aquariums increasing in popularity, it’s not surprising to see manufacturers jumping at the opportunity and producing so many different varieties of filters aimed at aquariums of smaller sizes.

In the end, we had to go with the AZOO Aquarium Mignon Filter as the best one available in the market. It’s incredibly compact, it makes barely any noise and it comes at a very reasonable price. 

We hope you gained value out of this article and have a much clearer understanding of what small aquarium filter to get. 

Let us know in the comments what filter you’re using in your small aquarium.

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