In terms of filter performance and supplies, aquascapes or plant aquariums have different specifications than a tank with high stocks of fish. We’ll explain what’s important to you.
In order to ensure good nutrient transport for the supply of aquatic plants, the flow in a densely planted aquarium should be adequate. Before purchasing you should inform yourself properly about the circulation rate of the filter, which is typically indicated in liters per hour.
For example: A typical 60 liter tank should be circulated five times per hour, for example. 5 x 60 gives a pump capacity of at least 300 liters per hour as needed.
There is an abundance of various filter media. These are roughly divided into mechanical, biological and chemical filter substances. Mechanical filtration corresponds to the filtering out of suspended particles, mostly by prefilters in the form of sponges, cotton or fleece. The principle of biological filtration is that bacteria colonize the corresponding filter materials, breaking down certain substances from the aquarium water by their activity. In chemical filtration, special materials actively influence the water through chemical processes and deliberately bind unwanted substances. These include filter materials such as activated carbon or phosphate adsorbers.
When you buy a new filter, there are usually different filter materials included already. Not all of them are necessary for the operation of a plant aquarium, though, and some might even be rather counterproductive.
The (permanent) use of activated carbon as a filter medium in a planted aquarium, which is fed with liquid fertilizers according to the plants’ needs, doesn’t make much sense. Although the activated carbon ensures clear water, it unfortunately also binds metals that are important nutrients for the plants. Iron and other trace elements fed through a complete fertilizer are removed by the activated carbon. In this respect, one should use activated carbon in a plant aquarium only under certain conditions, for example, only for a short period of time, to remove the residues from the water after e.g. a medication use against fish diseases.