How to Setup a Filter in your Aquarium (Step by Step Guide, FAQs & More)

We agree that setting up a fish tank filter can be a daunting experience. 

Luckily for you, we’ve come up with this easy-to-read guide to help you figure out the quickest and easiest way to set it up in your aquarium yourself. 

By the end of today’s post, you should be confident enough to set up your fish tank filter whether it’s an internal filter or an under-gravel filter

How to Setup a Filter in your Aquarium (Step by Step)

How to set up an Internal Filter

Internal filters are by far the most common types of fish tank filters as they are the easiest to set up. Even still, we’ve brought you this guide to make sure you don’t miss anything. Internal filters are designed to be fully submerged in your fish tank and they work in this environment by sucking in water, pushing it through its filter cartridge and then adding this water back into your aquarium.

Step 1: Find a Spot for the Filter on your Fish Tank 

Before doing anything, you should observe your fish tank and figure out what spot would be most suitable for you to mount your filter. It’s preferred that you leave a space of about 5 inches between your aquarium and the wall so that this can accommodate your filter

Also be sure to choose a spot for your fish tank filter where it would sway the water from the back of the fish tank to the front. This will cause it to spread CO2 and oxygen in the water in an efficient way. 

Step 2: Install the Filter Cartridge into the Filter 

A filter cartridge contains activated carbon that helps your filter neutralize any dangerous toxins present in your tank water. 

Different brands have different ways to install this cartridge into the filter so make sure to read the instructions that come with your fish tank filter  and install it accordingly. 

Step 3: Mount the Filter to your Aquarium 

Mount your filter to the place you chose for it on your aquarium. Most internal filters come with suction cups that grip themselves to the wall of the aquarium. Make sure the filter is firmly attached to the aquarium. Remember that this filter is going to be in contact with water and secure it to your aquarium’s wall accordingly.

Step 4: Fill the Aquarium with Water

How to Setup a Filter in your Aquarium (Step by Step)

Fill your aquarium up to your filter to the point where your filter is fully submerged in your tank water. 

Once you’ve filled your fish tank up, check all the necessary tubing. Especially make sure that the waste hose goes up to the surface as this is important for the discharge of wastewater. 

Step 5: Connect the Filter to the Power Supply and Turn on

Double-check that your filter is appropriately submerged into the tank water before connecting it to your power supply. 

Once you turn your fish tank filter on, you should begin to notice bubbles as the filter starts sucking in water to pass through the filter cartridge.

Check up on your filter after a few hours to make sure it’s working properly and pat yourself on the back on a job well done.

How to set up an Under-Gravel Filter

Under-Gravel filters work very discreetly but are more labor-intensive to set up. You might have to put in more effort in setting up this fish tank filter but we guarantee that it will be a rewarding experience in the end. Under-Gravel filters are amazing when it comes to biological filtration of the water as their constant low-flow suction aerates the entire aquarium and produces an environment that stimulates the growth of beneficial bacteria within the gravel and rocks of your aquarium. This growth will not only be beneficial for your fish but also for any live aquatic plants that you have in your aquarium

Step 1: Place Filter at the Bottom of the Tank 

As the name suggests, Under-Gravel filters are located underneath the gravel in your aquarium. Hence, you have to place your filter underneath your fish tank before you place anything else inside it.

Step 2: Cover it with Gravel and Rocks

Once you’ve securely positioned your filter underneath your aquarium, you can cover it with gravel, rocks and any other ornaments that you may have bought for your fish tank. It is preferred that you use these ornaments to completely cover up any filter equipment that may be showing up in your aquarium.

Step 3: Ensure Filter is Securely Positioned 

You must’ve done this in the first step as well but once you’ve put in all the gravel and rocks, there’s a tendency that the filter may become dislodged or mispositioned. Ensure that the filter remains in its correct position once you’re done adding all the gravel, rocks, ornaments and decorations into your fish tank.

Step 4: Connect Pump Carriers, Power Supply and Waste-Water Tubes 

Under-Gravel filters are more labor-intensive because of the more complicated filter grid that runs underneath the aquarium. Once you’ve topped it up with gravel, you should look to the bottom and connect all of the important tubing to its appropriate sockets. This includes any air pumps, waste-water tubes and power supply cables. 

Step 5: Fill Aquarium with Water

Finally, fill your aquarium with water. As the filter is located at the bottom of the aquarium, you need not worry about the water level. Just fill it up all the way as you normally would. Keep an eye on your filter all the time that you’re pouring water into your aquarium to ensure it does not get dislodged.

Step 6: Turn Filter’s Power Supply on 

Double-check all the wires, tubings and hoses and then turn your filter’s power supply on. You should begin to notice low-flow suction near the bottom surface of your aquarium as the filter starts to suck in water to pass it through its filtration chambers. 

Keep an eye on your aquarium for the next few hours to ensure it’s working properly.

Finally, congratulate yourself on a perfect installation job.


Many people tend to skip getting fish tank filters exclusively because they are intimidated by the installation process. 

We have to stress that a filter is not something you can skip and with a little bit of research and careful reading of the instructions, you can easily set up your fish tank filter properly in no time. 

We hope this post was helpful for you. Please give us feedback and let us know how you set up your fish tank filter.

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