100 Level

102 - Chapter 1

Putting It All Together

Pumps produce both flow and pressure; flow is pretty easy to see, especially over a waterfall, but pressure is hard to visualize. The concept of Head Height is an easy way to visualize the pressure a pump produces. One Pound per Square Inch of pressure will lift a column of water 2.31 feet in the air, so a pump that has a shutoff height of 23.1 feet produces 10 psi of pressure. This matters because the higher a pump has to lift water, the less water it can deliver. It makes sense that a given pump will deliver more water to a lower waterfall than a higher one. Head Height charts or graphs tell you exactly how much volume a pump will deliver to any given height, as in “2400 GPH @ 5’ of Head”. What you’ll need to know, then, is the head of your own system. In a perfect world, the head of a system would equal the highest point above pond’s surface, so a four foot high waterfall would give you 4 feet of head, but nothing’s perfect. The water from the pump is carried to the waterfall via tubing, and the size of the plumbing really matters.