Calculating Pond Head Pressure

Head pressure is the resistance a pump must overcome to pump water out the end of a pipe. In the case of a pond, after traveling through a filtration system, the end of the pipe might be the top of a waterfall or stream, or it might just lead straight back into the pond. When designing a pond pumping system, it’s important to think about efficiency. Higher efficiency means there’s less resistance for the pump to overcome to get water from the pond, through the filtration system, and out through the waterfall. Less resistance for the pump means that more water will flow out the end of the pipe for the same amount of work.

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Head pressure is the resistance a pump must overcome to pump water out the end of a pipe. In the case of a pond, after traveling through a filtration system, the end of the pipe might be the top of a waterfall or stream, or it might just lead straight back into the pond. When designing a pond pumping system, it’s important to think about efficiency. Higher efficiency means there’s less resistance for the pump to overcome to get water from the pond, through the filtration system, and out through the waterfall. Less resistance for the pump means that more water will flow out the end of the pipe for the same amount of work.

This is sort of like a car on the highway. A car will usually slow down on a steep hill, but will still use the same amount of power to overcome the hill at a now slower pace. Similarly, a pump will slow down as the head pressure increases, causing less water to be pumped out the end of the pipe.

There are a few things that increase the head pressure in a pumping system. The most obvious head pressure increase is the height of the waterfall or stream above the surface of the pond. For example, if you have a 5’ high waterfall, you will immediately have 5 feet of extra head pressure added to the system. Other things that add head pressure include filters, pipes and fittings. The diameter of a pipe can also have a large impact on the head pressure if the diameter of the pipe is too narrow for the given flow rate.

When you buy a pump, the specs will tell you how many gallons per hour will be pumped given a certain head pressure. For example, a pump may put out 2000 gph (gallons per hour) at 2’ of head, but when that’s increased to 10’ of head, which is more realistic for a pond, the flow may reduce to 1000 gph. This is why it’s very important to consider the head pressure of a pond system BEFORE choosing a pump! If the head pressure is ignored, it’s very probable that an incorrectly sized pump may be purchased.

If you’d like to learn more about head pressure, including the difference between static and dynamic head pressure, along with concrete examples of how to calculate head pressure for real-world pond scenarios, we recommend reading our ebook “How to Build an Ecosystem Pond”, which is available for sale on our site. In addition to discussing many other pond-building topics, this ebook goes into much more detail about head pressure than is discussed on this page.

If you’re looking to get started as soon as possible and need to choose a pump, we’ve developed a couple easy tools to automatically calculate the head pressure in your pond.

1) Pump Selection Wizard – this wizard will ask you a few simple questions, and will calculate the approximate amount of head pressure for your pond.

2) Advanced Head Pressure Wizard – this is a more advanced version of the simple pump selection wizard mentioned above. It’s meant for more complicated ponds, or for situations where very accurate head pressure numbers are desired.

 

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