Mary Allen
The filter is not only responsible for removing suspended matter and dirt particles from the water. With the help of microorganisms that colonize the filter materials, the filter system breaks down harmful substances into harmless, sometimes useful substances. These are evenly distributed in the pool by the generated water circulation, which also provides additional oxygen in the water. There are internal and external filters for the different aquarium sizes, which, with the right filter materials, help to maintain the biological balance in the aquarium.
Internal Filter for Small to Medium-Sized Aquariums
Internal filters are suitable for use in smaller aquariums with a water volume of up to around 100 liters or in addition to a biological external filter. The filter should completely circulate the aquarium water at least twice, even better three times per hour. The internal filter consists of a pump, a filter head with a suction opening, and the filter material (further information on this can be found below in the text).
Set up an Internal Filter in the Aquarium
Depending on the model, the filters can be built up modularly. With the common internal filters, you can adjust the flow rate and flow direction of the water as well as the use of filter media individually to the needs of the aquarium inhabitants. With the help of suction cups, the system can be attached to the pool glass in no time at all. When setting up new aquariums, it can take a few weeks (break-in phase) until the bacteria have settled in sufficient numbers on the filter material to fulfill their task of cleaning the water.
Please note: When planning your fish stock, you should consider that the internal filter takes up space in the water and reduces the water volume according to its size.
With an external filter, the water to be cleaned gets into the filter with the help of a suction pipe. The filter bacteria are located there to clean the water and filter out the suspended matter before it is pumped back into the pool through an outflow. An advantage over an internal filter is that you can use different filter materials made of ceramic, foam, fleece or, if necessary, activated carbon for a few weeks at the same time.
As the name suggests, external filters should be installed outside of the aquarium – for example, next to the aquarium or in the base cabinet. As a result, the filter system does not reduce the volume of water in the pool. The size of the external filter depends on the capacity of the aquarium. Aquarists usually calculate with 1.5 liters of filter volume for around 100 liters of water. In aquariums with a high stocking density such as Lake Malawi aquariums or fish that drop a lot of feces, it makes sense to increase the filter volume significantly or to add an internal filter.
Types and Properties of Filter Materials at a Glance
Different types of filter materials perform different tasks for water treatment, which you can combine with each other:
Mechanical Filter Media
The mechanical filter media remove coarse dirt particles such as suspended matter from the water. The most commonly used materials include foam sponges, fleece inserts, and various filter floss. The effect of mechanical filter media is simple: they catch the dirt from the water and hold it without leaving any residue. But they also offer countless bacteria a place on their surface.
Biological Filter Media
Glass-ceramic or clay tubes, Lavalife, granules, and bio-balls are among the biological filter media. Their often porous surface serves as a settlement area for the bacteria that are important for water purification. These bacteria break down the toxins in the water by using their metabolism to convert “bad” substances into “good”. High oxygen content in the water contributes to the fact that a sufficient number of microorganisms can accumulate in the aquarium.
Chemical Filter Materials
The most commonly used chemical filter material is activated carbon. Thanks to the comparatively large surface, coal is able to bind many dangerous substances. In addition to toxic compounds and heavy metals, this also includes dyes and medicines that may have been used to treat an illness. It is important to know that the activated carbon releases these substances again after some time. It should therefore only be used briefly and when needed.
Pea Filter
In addition to the filter materials that clean the water, there is the peat filter. It enriches the water with humic acid, which kills germs and keeps the germination rate in the lower range. However, the peat has an impact on the water parameters and also makes the water darker. You should find out beforehand which fish species prefer this type of water.
Clean the Internal and External Filters in the Aquarium
The internal filter does not require hose connections as it sits in the water. This makes it quick and easy to clean. Filter maintenance and care are due at least every fourteen days. Care must be taken when removing the filter, as the filter can lose dirt particles that get into the water and contaminate it. You can prevent this by holding a small bucket or container under the filter before removing it.
The external filter should only be serviced when its performance drops significantly – but no later than after two to four months. This depends on the type of aquarium and the fish stock. Before cleaning, it is necessary to clamp the hoses.
When it Makes Sense to Replace Filter Materials
When caring for the filter materials, it is not important that they are clinically clean in the end. On the contrary: Only remove the coarse dirt so that as many bacteria as possible are retained. The best way to do this is to use some fresh aquarium water to rinse off the filter material.
Please note: As soon as the filter is stopped, a relatively large number of bacterial strains die off. After half an hour of filter failure, all bacteria are usually dead. Then the filter must be completely cleaned. So don’t take too much time. A complete replacement of the filter materials only makes sense when the filter is really dirty and can no longer do its job. Individual materials such as clay tubes or fleece should always be replaced one after the other in order to retain as many bacteria as possible.