25 liter Gravity – pond cap. 4000 l (250BB)

Built-in systems (Gravity fed system)

This is the preferred system used on larger ponds, its biggest disadvantage is that it needs to be built into your pond at the beginning and is not an easy job to retro fit to an existing pond. The filter you build must be specifically designed to work with a gravity feed and the filter must be set at a height so the water level in it is the same as the water level in your pond. Depending on the type of pond you have you may have to dig the filter in, to achieve this.

External gravity filters: (Gravity return system)

External gravity filters have some advantages over built in systems as they do not need to be built in, are portable for ease of maintenance and must be set to gravity to gravity to return to the pond and thus the level inside the filter will be higher than the pond water level.