The Flow-Guard underdrain is made up of a series of stainless steel wedgewire “elements” attached to a stainless steel spoke system that covers the entire bottom of the tank. The large spoke system allows for a better distribution of the backwash water to the individual wedgewire

elements. The wedgewire is effective in preventing media from entering the irrigation system and by design does not get obstructed with media.
 

Covering the wedgewire elements is a layer of gravel. The purpose of the gravel is to deflect the high-velocity backwash water and create a very uniform flow, capable of gently lifting the media in the most efficient manner possible. Efficient backwashing results in cleaner media sand and shorter backwash cycles.