Bottom filter (UGF, RUGF) is widely used in fish aquariums. Regarding its use in the aquarium with plants, there are constant, non-ceasing disputes. Some things grow well with the use of a bottom filter, others fail. Of course, in addition to the presence or absence of a bottom filter in an aquarium, there are many other factors that influence plant growth. However, we can say that the use of such a filter has a minus (in addition to the other minuses that any filter has) that nutrients from the soil are washed into the water, where they become food for algae. In a plant aquarium, this is more critical. My practice has shown that the use of a bottom filter will not lead to better or worse growth of plants, while other conditions are fulfilled (light, fertilizer, etc.). It will make the system more unstable, i.e. if you overlooked something, the algae will appear faster than in an aquarium without such a filter. Usually it is necessary to increase the thickness of the soil (bottom layer, when laying the soil in layers). You should also make sure that the gravel does not fall through the filter board, for example, put a grid. Unfortunately. This leads to a decrease in the efficiency of the filter.
You can refuse to use the bottom filter in its original form and use it in a slightly modified form. Used fee from the bottom of the filter and two tubes. In one, water rises using a pump. The other is open, you only need to put a grid with large holes so that the fish do not swim out. Through this tube, water is sucked under the board. In this scheme, the pumping of water through the ground practically does not occur (in a long aquarium, you can do several intake tubes).
Do not put a sponge or filter on the intake tube, since as water is polluted, the flow of water through these openings will be limited, which will lead to water being pumped through the ground.
This scheme does not have the disadvantages of a bottom filter. True, it does not filter. Its advantages include:
- The lower layer of water is saturated with oxygen, which reduces the likelihood of the formation of oxygen-free areas in the soil.
- Down comes warm water from the aquarium. This leads to a more uniform temperature in the ground. Many plants like to keep their feet warm. You can additionally put a weak heating pad (5-10 W) for water heating. A stronger heater would create a backflow of water in the intake tube.
- CO2 can be introduced into the intake tube if you use it. At the same time, you can see how the bubble tries to rise in a downward flow of water and dissolves rather quickly. True, I later abandoned this method due to the fear of creating water with a low pH under the ground while dissolving CO2.
- In the initial period, you can close the intake tube and pump water through the ground. This will lead to more rapid decomposition of peat and earth in the initial period of launching the aquarium.
It should be noted that such a system must be cleaned, because after some time it will begin to overgrow with dirt and bacteria under the filter board. This can be done using a brush on a long wire, which is inserted into the intake tube. You can also insert a hose into which to pour water from the tap, and pump water from the second tube out of the aquarium. The hose should be driven under the filter plate to better remove dirt. Therefore, do not put the grid at the bottom of the tubes, which are usually included in the set of such filters – it will interfere with cleaning.