Best Internal Filters For Aquarium-Buying Guide

An internal filter or an external aquarium filter is better

The internal filters for aquariums and fish tanks are those arranged inside the aquarium. This is its main difference with the external filters, for which we need to enable a hole in the side or back of the aquarium, or when they are very large, have a cabinet enabled for this purpose, if you do not want it to be in sight (quite unsightly).

At first glance, it may seem that introducing an internal aquarium filter steals space that can be used for fish or plants in the aquarium. The truth is that they are not that big, and there are always dead spaces in the aquarium where to install them: corners, back of the plants, behind the decoration, etc.

Main characteristics
What you can be sure of is that they are quite popular. I would stress that they are filters:

  • Silent
  • Quite simple to operate
  • Ideal for small aquariums (which are the majority)
  • And above all, cheap. The perfect solution when you need to have an “extra” filtration system, which helps the main team to solve problems, such as the famous “dead center”

How an internal aquarium filter works

An internal aquarium filter is no different from any other external or backpack aquarium filter. Most internal aquarium filters can be placed vertically and horizontally, you should take this into account when choosing the best filter for your aquarium. The advantage of either arrangement is that it can be concealed behind the decoration.

Basically it works as follows:

  • At the bottom of the filter, there are a number of openings where the filter absorbs water from the aquarium, thanks to its internal pump.
  • Mechanically, the water passes through the different filter materials, usually foamex sponges and ceramic balls or cuvettes. The amount and variety of filter materials depends on the filter and its size.
  • The clean water is then discharged into the aquarium through the diffusers. Some filters include air diffusers, and others allow to regulate the water flow.

How to install an internal aquarium filter

There are two basic questions when installing an internal aquarium filter, where it should be installed and how to do it. The right place is as close as possible to the bottom, as I mentioned before, can be placed even in horizontal position, so that the space it occupies is smaller and goes unnoticed.

Another option is to install the filter in a corner of the aquarium, but it will depend on the design of the filter. As for how to place the internal aquarium filter, you must be careful to put the clean water outlet so that it is able to move the aquarium surface, to achieve better gas exchange and oxygenation of the aquarium.

Guide to buying the best internal aquarium filter

The best internal filters for fish tanks are those that cover our needs. Not everyone will need the same filter, because we do not all have the same type and size of aquarium, so to think that “this” or “that” are the best filters without an objective reason, does not help much.

To choose the right filter, you have to take into account:

  • The size of the aquarium. And depending on the size, consider the following features
  • Water flow that is capable of purification. It is measured in liters/hour.
  • Water flow. Some fishes want a strong water flow, while others like calm waters, preferably you have to choose filters that allow their regulation.
  • Directional control of the water flow. I explain it to you, because if you want the water to fall in the form of a waterfall, from the side, from the front…. read more about this feature below.
  • Additional aeration. Great when we want to increase the presence of oxygen in the aquarium water.
  • Types of filtration. Do you know how many types of water filtration a filter can do? Read a bit more about it below.
  • Filter size.

Advantages of internal filters for aquariums

No risk of water leakage
And even if it did, it wouldn’t cause any kind of damage.
The filters that are placed outside, if they have a water leak, can be a real problem. The best ones usually have leak detection, to stop their operation.
In any case, problems would arise, either for the fish and the aquarium, or for the integrity of our home.

They do not take up “extra” space outside the aquarium
Even if the detractors of the internal filters always talk about the space they steal from the aquarium, they never notice that the external filters do the same, but outside the aquarium.
Depending on the size of the external filter, this can also be a problem. They are large, unsightly and need space to be placed… not to mention that they are more complex to operate.

Useful for all types of aquariums
It is common (I mentioned it at the beginning of the article) that it is stated that internal filters are for small aquariums.
Yes, but it depends on what we mean by small. As you have seen in my selection, there are internal filters from 100 liters onwards.
What there are not are internal filters for 500 liters aquariums.

They are cheap
Internal filters for fish tanks and aquariums are much lower in price than backpack filters or external filters.

They are easy to install and maintain
They are usually filters with a very basic installation, which does not need to do anything, just place it inside the aquarium and plug it in.
Maintenance is also very basic. The best ones allow an easier access to the filter material, but in any case, they are easy to maintain.

They are quiet
They don’t usually make much noise, because they are also often turned off by the water in the aquarium, so they are ideal when we have an aquarium in a bedroom, or a study room.

Disadvantages of internal aquarium filters

Limited filtration
There are no internal filters for large aquariums. Internal filters can be installed in aquariums up to about 250 liters, or as an auxiliary filter in a large aquarium.
If you have a large aquarium, you must find an external filter.

They are limited in function
There are very good internal filters, which allow all kinds of filtering, orientation… but they always have less functions than the external ones, or we are going to find external filters with many more functions.

They occupy an interior space inside the aquarium
As I said, there are always dead spaces where to place an internal filter, but it is undoubtedly that they occupy a space inside the aquarium, which could be occupied by fish or plants.
We need a filter, whether it is inside or outside the aquarium… and each one will occupy its space, whatever it is.

They are in sight
This is unavoidable. An internal filter is seen, yes or yes.
The only thing left is to hide it, as long as we have some way to do it. In a very small aquarium, we may not have the option of plants and we will have to look for some kind of decoration, and in the worst case, it will be seen.

What is the best internal aquarium filter on the market?

Internal aquarium filter, tabThe internal filters for aquariums and fish tanks are the most commonly used in aquatics. This predilection is most evident in small aquariums. I can think of several reasons, the first being that most aquarium kits have internal filters as standard, and since hobbyists who are starting to breed fish for the first time are the ones who buy them, when the filters have to be replaced they prefer to continue using similar ones.

Although internal aquarium filters may seem to be the most humble, you should not be wrong. There are very good internal filters and many professionals use them in large aquariums, as an auxiliary filter for areas where larger filters cannot reach, or as a reinforcement to the one they already have in the aquarium.
In this shopping guide, I will tell you how to buy the best internal aquarium filter, according to its characteristics.