The new modern multi-chamber filter systems have a multitude of innovative functions that considerably simplify connection, operation and ongoing maintenance. simplify connection, operation and ongoing maintenance. The filter systems are available in three different sizes and can thus be individually adapted to the respective aquarium size. All filter systems are equipped, depending on the size, with one or two filter containers as a mechanical pre-filter, a skimmer chamber, a pump chamber, electrode holders as well as connection holders for dosing solutions. All filter systems are equipped with a refill container. The water level in the skimmer chamber can be adjusted to the The water level function allows the water level in the skimmer chamber to be optimally adjusted to the requirements of the respective skimmer, thus optimising the skimmer performance. The filter chambers have supply lines with common connection sizes to simplify the connection to the overflow of the aquarium.