100 Level

101 - Chapter 1

Pumps push, they don't suck.

  The most common pumps in Water Gardening are submersible centrifugal pumps. These use spinning blades or vanes to push water. The way the motor spins the impeller varies, but all centrifugal pumps work the same way. A chamber or volute with a central inlet and side mounted outlet surrounds the impeller, the business end of the pump. Spinning blades or vanes on the face of the impeller sling the water out of the chamber at a 90 degree angle, through the outlet and up the pipe. It’s important to remember that pumps push, they don’t suck. The void left by the water leaving the chamber creates an area of low pressure at the inlet that draws more water in, which in turn gets slung out by the impeller. The cycle continues and the water goes up the pipe. This is important because it explains why centrifugal pumps have to have water in the volute to start up. It also explains why there’s a big difference between dropping a submersible pump into a skimmer and correctly plumbing an external pumps.