If you are looking for some things to keep your aquarium tidy, ensure the water is healthy and clean for your fish, but also compact in size, so the internal fish tank filter is an ideal option for you.

The internal filter will help you save the space on the outside of the tank. Internal filter is smaller than other types of filters and should be used for small or medium-sized aquarium.

This post is the best internal aquarium filter review that will help you choose the right equipment for your tank by introducing to you two best internal filters: Fluval Underwater Filter VS. Tetra Whisper In-tank Filter with BioScrubber.

#1 Internal filter capacity

A filter cannot work with all the tank size. The manufacturer will always show the capacity of the filter in the description.  The capacity of the filter will be determined by how the amount of water it can handle.

Ensure that you will not choose the filter with the capacity is less than your tank capacity.

Fluval Underwater Filter is designed to work for 20-40 gallon tanks. Means while Tetra whisper is specifically designed for tanks containing from 3 gallons to 40 gallons of water.

#2 The filtration technology 

Each brand and model will use its own filtration technology. Tetra Whisper catches the derris, fish waste, algae that contain in the tank water by the sense, dual-sided mash.

It is also come with the large easy to change Bio-Bag cartridges. Tetra Whisper filter is mounted inside the aquarium, it allows to place the tank flush against the wall.

Fluval filter provides complete and efficient 3 filter media. Including 2 foam pads, 2 poly/carbon cartridges and 65 grams BioMax. It is filters debris and provides optimal biological filtration.

#3 Water-flow rate

The water flow rate is measured in gallons per hour. You will want filters that fill your fish tank faster. But the flow rate too strong can make your fish get hard to swim in the tank.

Fluval filters come with three-way flow control and modifiable output. Although the flow output can be able to adjust, it would be a litter complex to adjust the rate of flow.

There are some users who complain that their fish be sucked in Tetra Whisper filter even when they are awake and swim strongly. The solution is that you can cover the water intake with a filter mesh.