Aquarium filter – the difference between life and death

Without a good aquarium filter, the aquarium fish and aquarium plants are short-lived. It doesn’t matter what you do or what you don’t do: without a good filter your aquarium will become a poisonous mixture with dead animals. This also applies if you do not clean your aquarium filter properly. Not intended and absolutely not necessary. Read here more information about the right filter for your aquarium and about cleaning it.

Quickly find the right aquarium filter?

A good balance in your aquarium water starts in your filter. Without balance you mainly have a lot of algaeDuring the past years I have tried a lot of filters and also got very mixed results. Leaks, blockages, stench, I have experienced everything. Now I have two aquariums, the smaller version with a cheap, good and modern Eheim internal filter that is easy to clean. For my 300 liter aquarium I use this external filter. That was one of my best investments. In addition, this filter is economical and quite quiet, which is important to me.

Why an aquarium filter?

If you wonder why an aquarium filter is necessary, it is very easy to answer with a counter question: Why do we have a toilet in the house?

Like other animals, fish secrete substances including feces and these end up in the water. The aquarium filter also catches other dirt that has ended up in the water and ensures that the water continues to circulate.

It contributes significantly to keeping the balance in the aquarium in order, so that the aquarium fish and aquarium plants remain healthy.

Tip: Place a screen in front of your aquarium filter so that smaller inhabitants such as shrimp cannot be sucked into the filter

Aquarium plants that are placed in an aquarium also have a purifying effect. The fewer plants there are in your aquarium, the more the filter will have to do. A freshwater aquarium with many well-growing plants requires less of a filter than a Malawi biotope. This requires much more from the filter, because there are hardly any aquarium plants in it. Aquarium plants are fundamental and have numerous benefits. Read the blog about aquarium plants for all the benefits.

Cleaning an aquarium filter, why and how often?

Cleaning the aquarium filter is a job that is simply necessary. In particular mechanical filters because the dirt sometimes tends to accumulate there. The biological aquarium filters should be less disturbed. You would like to maintain the bacterial colonies that have a purifying effect on your aquarium water. A big mistake is therefore that people clean their filters with boiling water.

Fun fact: a rule of thumb is that the larger your aquarium, the less often you need to clean the filter. Also read the blog about cleaning the aquarium for more information.
Of course for removing dirt and grime from the water
The water surface remains clean, the “haze” on the water also disappears.
Waste from, for example, your fish is neutralized
The circulation of the filter ensures that there are no ‘dead spots’. This prevents algae.
Depending on your filter, good biological substances can also be added.
Tip: Clean your aquarium filter in a bucket with your own aquarium water. This way you can rinse out the coarse dirt but keep the good bacteria.

Cleaning your aquarium filter is part of the whole. By the whole I mean the balance in your aquarium water. If the balance is right, your aquarium plants will also grow well. That is why periodic maintenance is necessary for your entire aquarium.


The filters that you can buy in the store are the inner and outer filters, which can be divided into mechanical and biological filters. That seems confusing, but it isn’t:

  • The inner filter hangs in the aquarium, the outer filter is an aquarium filter that is placed outside the aquarium
  • For example, a mechanical filter removes the visible dirt from the aquarium water, where a biological filter, filters and cleans on the basis of “good” bacterial colonies.

Because the internal filters take up a lot of usable space within the aquarium, an external filter is often chosen. The best choice is made by comparing the pros and cons. Okay, now we know why aquarium filters are important, but which ones do you need in your aquarium?

Aquarium aquarium filters
Biorb aquarium Internal filter
Nano aquarium External filter or small internal filter due to space
Aquarium up to 75 liters Internal filter
Aquarium larger than 75 liters Inner filter or outer filter
Malawi aquarium Biological external filter
Brakwater aquarium Inner filter or outer filter based on the size


You make the choice for an aquarium filter on the basis of the aquarium inhabitants and the size of the aquarium itself. The larger the aquarium and the more plants, the less the load on the filter. The smaller the aquarium and the fewer plants, the greater the load on the filter. It is wise to put the types of aquarium filters next to each other and make a choice from them.

Advantages of an external filter
Disadvantages of an external filter
Large filter with its strong effect A lot more expensive to purchase than an internal filter
Ensures adequate water circulation More cleaning work to get the different parts clean
Hoses are easy to get rid of Risk of leakage if connected incorrectly, the hoses often leak.
Possibility to connect peripheral equipment such as a CO2 installation. Extra space is needed outside the aquarium and of course you must have it
You do not have to enter the aquarium to clean the aquarium filter. Top! Installation is more difficult than an internal filter because there is something more involved with the connection.
You can hide the filter itself nicely under or behind the aquarium Strong current and therefore unsuitable for smaller aquariums with less than 75 liters


Advantages of an internal filter
Disadvantages of an internal filter
No chance of leakage, leakage in an aquarium is always no problem 😉 The filter is often smaller because you don’t want to lose all your space on it. This is at the expense of operation, but does not have to be a problem.
Easier to install, just plug in and voila. Cleaning must always be done in the aquarium and that will inevitably lead to flooding.
Provides sufficient circulation, provided you buy a good aquarium filter The filter is smaller and therefore needs to be cleaned more often than an external filter
Suitable for small aquariums Limited ability to connect peripherals
No space needed outside the aquarium Difficult to keep out of sight, there are some aquarium plants or decoration involved

Leave your questions in the comments!

Do you want to know more about how an aquarium filter works or do you just have questions about it? Then leave your question in the comments below. Do you have any tips for other aquarium enthusiasts? We would like to know that too!

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