Pond Filtration

There are 3 types of pond filtration: mechanical, biological, and UV clarification.

Mechanical Filtration

This type of filter comprises a coarse sponge that will help to remove debris from the pond.  Mechanical pre-filters are often built into pond pumps, to prevent debris from clogging the pump.

Biological filtration

If you plan on raising fish in your pond, it is essential that you have a biological filter.  Biological filtration removes fish wastes (i.e. ammonia) from the water.  This type of filtration works according to the concept of the Nitrifying Cycle:

1. Plants are consumed by fish.
2. Fish produce wastes (ammonia).
3. Beneficial bacteria convert the ammonia into fertilizer (nitrates).
4. Fertilizer is consumed by the plants (and thus, the cycle continues).

Coarse biological filtration is required to house a beneficial bacteria colony.

UV Clarification

UV Clarification helps to remove algae from the pond by zapping the water with a UV light.  UV clarifiers are often out-of-pond units that have to be fed water by a pond pump.

There also exist natural remedies for algae, which include (1) barley extract, and (2) increasing the level of pond shade.

Skimmers

A skimmer removes leaves and other debris from the top of the water.  As leaves decompose, they produce toxic gases which can harm your fish.  This is especially evident during the wintertime, when ice can trap these gases in the pond.

A skimmer functions as a mechanical filter. Netting within the skimmer traps debris, and a pump inside the skimmer works constantly to draw water into it.  Water from the skimmer can be pumped to a bio waterfall filter, or back into the pond.

A skimmer works best when it is installed downwind (the prevailing winds can direct leaves and other debris towards the skimmer).  To maximize water circulation, water should re-enter the pond at the opposite end of the skimmer.  The re-entry of water into the pond also creates currents that propel additional debris into the skimmer.