Why Build a Bog?

by: Demi Fortuna

Plants are a great help in keeping water clear and clean, and one of the best ways to optimize their abilities is in a Bog. Bogs are shallow planted gravel beds where water from the pond feeds colonies of beneficial bacteria growing right where plant roots can pull out the nitrates they produce. Removal of the nitrates by bog plantings effectively starves out both floating and string algae, at the “cost” of weeding out the bog plants once a year.

A Passive Bog just sits at the edge of the pond where water can seep into the gravel, but the most effective way to set up this all-natural filter is in an Active Bog, where a pump delivers a constant small flow of water through a perforated pipe right into the base of the gravel bed. Plants in the gravel have no soil to sustain growth, so they are forced to extract their nutrients directly from the water.

Sized properly, at about 10-30% of the total surface area of the pond, a well-planted bog can effectively remove all the nitrates, starving out algae and cleaning and clearing the water column. Whether passive or active, Bogs are easy to build into your new pond, or even to retrofit into existing water features, even Koi ponds!.