I recently built this overhead sump filter for nitrate reduction and to
add some additional bio-filtration. It's been running a few days and
already has reduced nitrates considerably.
The tank water is pumped up to the sump through a pond pump.
The overhead sump has bio ball media, and net pots with clay
pellet media. Plants are planted in the net pots. As water flows
through the sump, nitrates are removed by the plant roots. This
in turn feeds the plants to grow. The water then drops down two
drain hoses back into the tank.
Water is pumped at about 100 gph
through the sump, and supplements
a Cascade 1200 canister.
This has lowered my nitrate levels by 30ppm, to a much lower 10-15 ppm
. As the plants grow,
they will consume more nitrates. Making the nitrate level even lower.