Once you build a pond it is for life, so it is extremely important to get your design right. The picture explains a typical design that works. Isivande uses bead filter material not sand, which means you don’t have to stir the sand every time you backwash. The filter system works from the bottom up as all the beads float to the top. The dirt sedement gets blown out of the chamber via an air pump before the backwash cycle is done.
