More and More water filtering info

Some construction tips and slow sand technology.

BACKWASHING a biological sand filter when the flow rate slows down. Forcefully backwashing a slow sand filter, particularly a small slow sand filter with layers of different sizes of sand, will destroy it. The flow rate is slowed by a buildup of material on the TOP FEW CENTIMETERS of sand. Simply gently agitating this layer and DRAINING OFF the cloudy water is all that needs to be done.

Now for the main site - David H. Manz the inventor.