Learn what the term "water pump head" means, and maximum head

You may not be familiar with the term "water pump head." Basically this refers to the pressure that must be generated by a water pump in order to run a fountain, waterfall, filter, and other pond components

Most water pumps used in ponds are of the centrifugal design. In this type of pump, an impellor spins at a high speed, creating pressure by centrifugal force. This pressure pumps the water to whatever height is necessary to run your pond components, including a waterfall if you have one. An important consideration with these pumps is the fact that the speed of the impellor rotation is normally constant, which means the energy and pressure of the water pumped is constant. In practical terms, this amount of constant energy can be divided as follows:

Use this energy to pump more water volume to a lower head (height)
Use this same energy to pump less water volume to a greater head

By understanding these two options, you'll be able to quickly and easily determine the water pump specifications needed for your garden pond application. You can demonstrate the action of water pump head by doing the following:

Understanding pump head

To see the effect of pump head in action, you'll want to attach a length of garden hose to your pump (say 10 feet or so) and observe what happens as follows:

If you're testing a submersible type water pump, place the pump in your pond or other water reservoir and hold the end of the hose at the water surface level. You will observe that a large amount of water flows out of the hose.

Now, lift the end of the hose slowly above the surface of the water. You will see that as the hose rises higher into the air, the flow of the water decreases until you reach a point where the flow stops all together. If the pump you're testing is fairly small, with low maximum head, you might reach this break-even point at 6 feet or less. For a stronger pump, you might have to stand to a ladder to reach this point.

Pump head is just another term for pump pressure

Think of the head developed by your water pump--in practical terms regarding your garden pond situation--as the height to which the water will be pumped, either to the top of your waterfall, fountain, biofilter or other component. But keep in mind this is the distance FROM THE SURFACE OF YOUR POND (not the bottom where your pump resides) AND THE INLET TO YOUR WATEFALL OR OTHER COMPONENT.

In order to purchase the correct pump for your water garden application, you will have to determine the correct water pump head for your system. As stated earlier, there is a relationship between the height to which the water is pumped and the amount of water that is pumped -- ie the higher the head, the less water volume, and visa versa. This is due to the fact that the pump can only generate so much pressure, and the water has to be pumped against the force of gravity, along with the friction of the hose itself.

This relationship between pump head and water flow rate is very important, and you'll need to know it in order to choose the correct pump for your pond application, especially if you plan on having a waterfall with your pond.

A gentle warning about maximum head

You will notice when shopping for a water pump that maximum head is almost always stated on the outside of the box. But keep in mind that this can be a very misleading specification. In practical terms, maximum head as stated this way is almost meaningless, because at maximum head the water flow from the pipe is ZERO. Now obviously this will not do you much good when choosing the correct pump for your waterfall.

Another important consideration is the other garden pond components your pump will be supplying. When water is pumped through a pipe or tube with any kind of fittings, as in "T" fittings, in-line UV lights, etc, then some of the energy and pressure from the water pump is lost due to the restrictive nature of forcing the water through these fittings.

You need to take this pressure loss into account when determining the total water pump head of your pond system. This head loss is also known as friction loss. In practical terms if you have a small pond system with short lengths of pipe and relatively few bends and fittings this friction loss can almost be ignored as long as you do the following:

Use lengths of pipe or hose less than 10 feet (3 meters) long
Use pipe or hose with a diameter of less than 1 inch (25mm)
Use ribbed pipe. This type of pipe doesn't restrict pump flow when bent, as is often required in a garden pond application.

There are additional factors you'll need to take into account when choosing a pump, not the least of which is the pump flow needed for your pond. This pump flow will depend on whether or not you have a waterfall, if you plan on keeping koi or other fish in your pond, if you'll be running a fountain, etc.

When in doubt, it's generally a good idea to choose a larger pond pump than you think you might need. Knowing about water pump head will also give you leverage when dealing with retailers, who probably don't fully understand pump specifications themselves. Armed with this knowledge, you can usually bargain for a lower price, or at least insure that you buy the correct pump for you water gardening project.

Complete Pond Solver

More info or buy here

sitemap