What Does Pump Head Pressure Mean?
Published by Dan on Aug 7th 2018
Choosing the right water pump for your pond can make all of the
difference in the world. All pumps produce water flow and pressure.
Pumps are rated in Head Height which is an easy way to visualize the
pressure a pump produces. Naturally, a 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 at any given Head
height.
When designing your pond you will need to know the head height of your own system. It is not enough to know just the highest point above the pond as there are other variables to consider. The water from the pump is carried to the waterfall via tubing, and the size of the tubing and the number of fittings will come into play in determining what pump you will need. Both tubing and fittings cause friction resulting in a reduction of water flow which in turn can cause the pump to work much harder producing less flow. In order to keep this friction loss to a minimum, always increase the tubing at least one size larger (if possible) than the outlet of the pump. If the outlet is 3/4", use 1" or larger plumbing. If it's 1-1/2", go up to 2" tubing. There are several shortcuts in computing the total head required.
- For every 1' of Vertical Tubing, add 1 foot of Head
- For every 10' of Horizontal Tubing, add 1 foot of Head
- For every Check Valve, add 1' of Head
- For every fitting, add ½ foot of Head
Example: If your waterfall is 5 feet tall, with 20 feet of tubing and two elbows and a check valve, your system would have a total head of 5 + 2 + 1 + 1 = 9 feet of Head. With this information you can check the manufacturer’s pump graphs to see which pump gives the flow you need at 9' Head. In this example we did not calculate the addition of a pond pressurized filter which in itself can reduce the flow as much as 10-20%. In most cases it is better to opt for a larger pump as you can generally reduce the flow but if your pump is not large enough there is nothing you can do to increase the flow.