10 FAQs about Filters for Aquariums & Fish Tanks (Guide & More)

It’s hard to disagree with you when you say that buying a filter for your aquarium is not as easy as it sounds.

We found this out the hard way when we were experimenting with different filters in order to compile this article for you. We’ve come up with the answers to all the common mysteries surrounding fish tank filters.

In today’s post, we’ll be shedding light upon all the common problems faced by fish-owners when buying filters.

10 FAQs about Filters for Aquariums & Fish Tanks (Experts Answered) 2020

1. How often should the Filter Cartridge be changed? 

Most filters recommend that you do this once every month. This is because most filters contain carbon which helps remove a lot of harmful chemical substances in the water. But this carbon eventually “runs out” which usually happens after about a month. 

2. I have a very small Aquarium. Do I still need a Fish Tank Filter? 

This is a common question among new fish-keepers. It’s a common myth to believe that if you have a small enough tank, a filter is not required. This, however, is not true. No matter how small your fish tank is or how few fish you have, they are all still producing waste that contaminates the water and this water needs to be filtered and cleaned regularly.

Don’t torture your fish by skimping out on a filter. They will have to live in very poor water conditions and you’ll have to change the water a lot more regularly if you don’t invest in a fish tank filter.

3. How often should I clean my Filter?

The simple answer to this is to simply clean your filter when it becomes dirty.

However, there’s a lot more that goes into it. There are a lot of factors that can influence your decision about when to clean your filter. We strongly advise not to clean your filter if you’ve recently made some other big adjustment in your aquarium. Fish don’t like constant changes; it makes them stressed. So, if you’ve recently made some major adjustments and then you continue to take out your filter and clean it, this would be unkind to your fish.

Other factors that determine how often you should clean your filter is how many fish you have in your tank, your aquarium size, the amount of food you’re feeding them, etc. Obviously, a smaller filter that’s cleaning a large tank will need to be cleaned more often than a big filter that’s cleaning a small tank.

Generally, you should be prepared to clean your filter every two weeks or so.

4. What’s a good way to thoroughly Clean my Fish Tank Filter? 

A very important thing to consider when washing your fish tank filter is to wash it with tank water and not tap water. This is important as chlorine in tap water could kill off natural bacteria in the filter that could be beneficial to your fish. 

5. Do all Types of Fish roughly produce the same amount of Waste? 

This is definitely not the case. It depends on the fish type, size and a number of other factors. This is something you should consider before adding new fish to your tank.

For example, African Cichlids and Goldfish are much messier than fish like Neon Tetras or Danios.

If you have a filter that’s already working at its full ability, adding messier fish to your fish tank could render your filter ineffective. More waste-producing fish require stronger filtration in order to keep the same conditions in the water.

6. Can I immediately Use a Fish Tank Filter?

10 FAQs about Filters for Aquariums & Fish Tanks (Experts Answered) 2020

We recommend that you don’t do this. A fish tank filter often contains harmful toxins. These toxins need to be eliminated first. You can do this by “cycling” your aquarium. This refers to letting your filter rest in the aquarium for about two weeks so that natural bacteria can grow inside the filter and eliminate any dangerous toxins. Only after that should you start using it with your fish.

If you want to start using your filter immediately, there are Nitrifying Bacteria agents that you can buy in the market. They will allow you to get your filter started immediately though we prefer the former approach.

7. Can an Aquarium Filter be Used in a Planted Tank?

Yes. You can use an aquarium filter with your aquatic plants without having to worry.

Although, we would suggest that you don’t get under-gravel filters. All the other filters will work fine but under-gravel filters can be troublesome as the roots of your aquatic plants have a tendency to wrap themselves around the filtration system grid underneath the gravel.

Just make sure that whatever filter you’ve installed, it moves the water just enough for your plants to sway but not too much. This will help the distribution of CO2 in the water and stimulate growth in your aquatic plants. 

8. Is a Canister Filter Safe for Fish?

Canister filters work by sucking in water, filtering it and then pushing it back into the aquarium when it’s clean. There’s a common misconception that these filters aren’t safe and are hazardous when it comes to water filtration. There are horror stories on the internet about fish getting caught or sucked into the tubing.

However, these are merely just stories. Canister filters are completely safe for your fish and they work quite well in terms of improving the water quality and conditions of your fish tank

9. What’s the Average Price of Fish Tank Filters?

The cheapest tank filters around can come for about $20 whereas the more high-end ones can cost several hundreds of dollars. We recommend that if you’re a beginner, getting a fish tank filter within the price range of $50 – $150 is a good starting point.

The price range differs due to different factors such as the material they’re made from, water flow rates, capacity, etc. Larger capacity filters always cost more than lower capacity filters.  

10. Where Should I Mount my Filter on my Fish Tank?

This highly depends on the type of filter you have. Under-gravel filters, as the name suggests, are placed underneath the gravel in the aquarium, hang-on, internal and submersible filters are mounted to the sides of the aquarium and canister filters can be placed above or below the fish tank.

It’s important to note that wherever you place your filter, you should note that the water is being pushed from the back to the front as this helps distribute oxygen and CO2 throughout the water and is beneficial for both your fish and your aquatic plants.  


It is often quite difficult to make the right decision no matter how well-informed you are.

However, coming to the end of this post, we hope that we’ve supplied you with enough information for you to be confident enough to trust your own judgement when buying a fish tank filter.

Give us feedback and let us know what fish tank filter you’re using.

You Might Be Interested In...

Leave a Comment

Your email address will not be published. Required fields are marked *