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Pump head heights
Maximum pumping height (total head)
For vertical lift
For a given pump, the higher water is pumped vertically - the lower the flow; at a given height the flow will be zero. The terms "head height" or "lift" are used to indicate this vertical height, measuring how high the water can be pumped for a particular application. Each pump has a published graph showing its flow rate at various heads. Waterfalls or streams have the added factor of friction loss created by the longer hose run required between the pump and the top of the waterfall or stream.
Friction loss - for waterfall or stream use.
Pumping water through tubing adds resistance, so an allowance must be made for friction loss inside the tube. However as the size of the tubing has a significant bearing on frictional resistance, the use of an undersize tube will increase frictional losses.
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As a rule of thumb add 10cm of head for every 1 metre of horizontal tubing run |
+ 10cm |
An allowance for friction loss must be added to the vertical distance (in metres) measured from the surface of the pond, over which you will be pumping the water. The resulting sum will be the 'Total Head' that the pump will be required to lift the water. You should compare the flow rate that you require, to the flow rate that the pump provides at this specific head.
Elbows/Tee - The effect they have on flow rates
If you intend to have any tees or elbows in the plumbing system, you should allow for the loss of flow that an elbow or tee will create.
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As a rule of thumb at least an extra 25% of head height should be added for each one. | + 25% |
Example
The vertical distance between the pond surface level and the top of the waterfall is 1 metre. There is 6 metres of tubing between the pump and the waterfall. Your total head is 1.6 metres.
| Example | metres | |
| Vertical distance | 1.0 | |
| Horizontal tubing 6 metres | (10cm for each metre) | 0.6 |
| Total Head | 1.6 | |
However, if the more accurate tables below are used for the flow of 6,000 LPH you will see that the friction loss can vary between as little as 0.03 when using 1.5" hose up to a huge 0.34 when using 1" hose. In other words the jump is from 3% up to 34%.
Friction loss in hose chart
The chart below will show that there is a massive difference between flow and hose diameter. Doubling the diameter of the hose increases
the flow capacity four times -no wonder there is less friction per metre. For example 25mm hose is 490 square mm while 32mm is 804 and 38mm 1,256 square mm.
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Hose Flow Rates
The tubing size required at the pump is determined by the maximum flow rate of the pump selected. It is important that the diameter of the tubing chosen is appropriate for the volume of water coming from the pump. A hose adapter or a combination of adapters is required to attach the hose to most pumps. Following are the maximum flow rates in litres per hour (LPH) for various tubing diameters:
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(litres per hour) |
Short runs - (inside diameter) |
For longer runs - over 2m, go up a size |
| 1,000 |
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19mm - (3/4") |
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25mm - (1") |
| 4,500 |
25mm - (1") |
32mm - (1 1/4") |
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40mm - (1 1/2") |
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50mm - (2") |
| 18,000 |
50mm - (2") |
75mm - (3") |
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100mm (4") |
| If in doubt, always use a larger size tube (see friction loss chart above) | ||
If your pump appears not to deliver the amount of water it is rated for, perhaps you are using the wrong size tubing.
Recommended tubing sizes are listed for each pump that we sell. Please click on the pump model number for more details. The requirements of different pumps can vary and the above chart is meant as a guide only.
Progress
Actual Pond Volume
Effective Pond Volume
Maximum pumping height and tube friction loss
The weir rate for waterfalls and streams
Filter (if being used)
Power consumption
Weir rates for waterfalls and streams
Calculate the flow rates for your waterfall and streams >> NEXT >>
