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Pump Selection

From the smallest barrel garden to the largest koi pond, no water garden can survive very long without water movement. And for water movement a pump is essential because it keeps the water circulating and the pond healthy.

A cascading, bubbling stream adds interest and serenity to the garden, while a waterfall can create a dramatic centerpiece. Fountains, while aesthetically pleasing, provide the additional benefit of aerating the water, essential for providing a healthy environment for fish. Water must also be supplied to filters that help keep the water clear.

Our website includes a large assortment of submersible pumps from manufacturers like AQUASCAPE, OASE, FOUNTAIN SYSTEMS, PRO ECO PRODUCTS, ATLANTIC WATER GARDENS, PONDMASTER, MATALA, and many more.

When selecting a pump, be sure to look for the GPH for each head height, as well as the maximum height that the unit will pump. At maximum height (or max. head), the pump only puts out a trickle of water. A long-term manufacturer's warranty and energy consumption are also important factors.

Pump Selection for Circulation Purposes

To maintain a healthy pond, experts recommend circulating the water at least once every two hours. This means that for a pond with an effective volume of 3000 gallons, you will need to circulate at least 1500 gallons per hour (GPH). Hence, a pump capable of pumping 1500 GPH or more at the total head of your project is required. This is the absolute minimum amount of water that you need to circulate.

Small & Shallow Ponds (up to 250 gallons approx.)

Due to the special requirements and unique circumstances found in smaller and shallow ponds, including most pre-formed units, we recommend to turn the effective pond volume over once per hour.

If the effective volume of your pond is 150 gallons, look for a pump that can deliver 150 GPH at your total head. If you are pumping up to a small waterfall or cascade 2 feet above pond surface level, you need to pump 150 GPH at a 2 foot head. Also see Waterfalls & Streams below for additional information.

Waterfalls & Streams

Sizing a pump for a waterfall or a stream is usually quite simple. The first item to consider is to ensure that you are circulating the effective pond volume at least once every two hours. This would be the minimum flow requirement. The second and usually the most important factor to consider is the characteristics of the waterfall. This includes the amount of flow that you wish to see coming over the waterfall and the width of the waterfall.

Please take a moment to review how to calculate the total head requirements for your waterfall.

Assuming you want to operate a waterfall with a vertical head of 3 feet (vertical distance from pond surface level to top of waterfall) and you will have 10 feet of tubing between the pump and the top of the waterfall. You will have a total head of 4 feet. The smallest pump that you should consider would be one that is capable of circulating half the effective volume of the pond at a total head of 4 feet. Assuming an effective pond volume of 3,000 gallons, the pump that you choose will have to be able to deliver 1,500 GPH at a 4 foot head. This is the minimum requirement for
circulation purposes.

Place your pump as far away from the waterfall as possible to maximize circulation within the pond.

When operating a waterfall, another important consideration is appearance. Depending on the width of the waterfall lip (weir) or stream and your expectations, half the effective volume may or may not be adequate.

The next step is to determine the flow requirements of your waterfall to achieve the type of effect you desire. You may need to consult the waterfall weir chart for more details.

As a rule of thumb, 100 GPH per inch of waterfall/stream width will provide a good flow equal to a sheet of water approx. 3/8" thick over a stone waterfall weir 12" or wider.

Assuming the waterfall is 18" wide and using the 100 GPH per inch guideline, you should select a pump that can deliver 1,800 GPH (100 GPH x 18" width) at a 4 foot head (as calculated above). This is slightly more than the 1,500 GPH that the 3,000 gallon pond in our example requires for circulation purposes alone but will result in a more aesthetically pleasing display. Within reason, circulating the effective volume of the pond more frequently will not harm the pond.

Once you have determined the volume of water that you will require, go to our main pumps page and select an appropriate pump. In this case, you would look for a pump in the 2,000 GPH max. output range because you require 1,800 GPH at a 4 foot total head.

A suitable selection for our example would be a Supreme Pondmaster 2400. The final selection is up to you.  Criteria would be initial cost, power consumption, and manufacturer's warranty. The yearly operating cost  comparison figures on the website make it easy to determine which pump will be most ecomomical to operate
 over the long term. Sometimes, a less expensive pump with a high power consumption will end up costing you  more in the end.

If you would like to see a higher amount of water pumped over your waterfall, simply multiply the required GPH x the width of your waterfall in inches (see waterfall weir chart). For example, a 3/4" thick sheet of water over a 12" wide waterfall will require a pump that can deliver 3,300 GPH at the total head of your waterfall (275 GPH x 12" width). If your waterfall is 18" wide, your pump would have to deliver 4,950 GPH (275 GPH x 18" width) to get the same 3/4" water coverage. As you can see, the wider the waterfall, the greater the volume of water that is required.

Make sure your lower pond is sized in relation to your waterfall and the pump's output. This helps ensure an adequate water supply for the pump at all times and helps contain any splash that the waterfall may cause.

If half the effective pond volume once every 2 hours is too much flow for your waterfall, we recommend to split the flow coming from the pump discharge by using a hose tee and diverting part of the flow to another water feature or to the other side of the pond to maximize circulation. You may have to install a ball valve in one or both of the lines to control the amount of water going in each direction.

All that is left to do is to choose the correct size of tubing as dictated by the maximum flow rate of the pump you select. Recommended tubing sizes are listed for each pump that we sell. Please click on the pump model number for more details. As each pump has different requirements, the tubing flow rate chart is meant as a guideline only.

If the pump you are using is not listed on our website, you may want to consult the tubing flow rate chart to determine which size is most appropriate for the pump.

A hose adapter or a combination of adapters may be required to connect the tubing to most pumps.

If your pump does not deliver the amount of water it is rated for, perhaps you are using the wrong size tubing.


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