Bio Filters (Gravity Feed)
Do you have a cloudy pond, suspended algae or other particles that have turned the water green?
A simple option is to add an in-line UVC clarifier in the water circuit of the pond, ideally upstream from your filter or add a Filtration system with a UVC light.
The ultra-violet clarifying light inside the system kills off the suspended algae, and bacteria and germs are eliminated.
A filtration system with a UVC light added (or included) will filter the dead algae and debris through a sponge system before returning the water to the pond.
Access to power is required.