External gravity filters have some advantages over built-in systems as they are portable for ease of maintenance. They must be set to return to the pond by gravity and thus the level inside the filter must be higher than the pond water level.
The UV Sterilizer helps keep the water clear by killing off the free-floating microorganisms.
These units come with foams, gauze and bio-balls.
8W /15 litre - pond cap. 1200 l
8W /25 litre - pond cap. 4000 l
15W/50 litre - pond cap. 10000 l
15W/100 litre - pond cap 12-14000l