Can anyone advise on how to calculate the pump flow rate required to pump the amount of water from my lower pond to the upper pond, to replace the water which has flowed out over a waterfall into the lower pond. The two ponds completely separated and the waterfall, a block of sandstone, hangs over the lower pond allowing water to flow from the upper to lower pond. I hope this make some sense and thanks very much for any help.
pond pump choice
- Thread starter Liamondo
- Start date
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Perhaps I'm being stupid, but does your waterfall flow over an edge that is higher than the bottom of your upper pond?
If so, it doesn't matter about pump flow rate. Whatever the pump is capable of delivering will equate to the amount of water flowing in your waterfall.
If so, it doesn't matter about pump flow rate. Whatever the pump is capable of delivering will equate to the amount of water flowing in your waterfall.
What he said - you could probably over-do it if you get too big a pump but it's fairly unlikely. As you're not doing it for filtration purposes then you don't need to worry about volume turnover etc.
Best bet I reckon is to stick a hose into the upper pond and turn the tap up slowly until you're getting the kind of flow over the waterfall that you want - when you've got that pull the hose out and time how long it takes to fill a measured container e.g. a 2 litre drinks bottle (or bigger if possible) then use pencil and paper etc (or http://www.1728.org/flow.htm) to work out your required flow.
Once you know this you can go pump shopping - you can get a pump with a higher rating as most of these pumps are centrifugal so you can throttle the output (reduce the flow) without doing any damage to the pump but it will of course use the same amount of power.
Also you need to consider the hydrostatic head the pump will be working against to lift the water up from the bottom pond to above the top (measure from the water surface in bottom pond), most manufacturers will quote flow rates at more than one height e.g. 200lph @ 0m, 900lph @ 100cm etc.
Also remember to have the pump outlet above the water line in the top pond otherwise if the pump fails (power cut etc) you will get a syphon running top to bottom and a potential flood.
Also remember to have the pump outlet above the water line in the top pond otherwise if the pump fails (power cut etc) you will get a syphon running top to bottom and a potential flood.
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Also consider your volume changes. When the pump is not running all the "moving" water in the pump system will dump into the lower pond which may make it overflow if its much smaller, likelwise when the pump comes on the water level in the lower one may drop too much if its not large enough
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