Pond Pump Calculations

General Guide...
To point you in the right direction follow this basic guide which will calculate the size required for the three common uses of pump, and then have a chat with one of our experts to confirm your choice.

Are You Having A Waterfall?
The wider you wish your waterfall to be, the greater the flow required for it to look effective. To calculate the required flow, follow this simple formula.

A	Width of Spill	Multiply by factor	Equals flow required
	_____ cm	Multiply by 91	_____ lt/hr
	_____ in	Multiply by 50	_____ gal/hr

**Example**
A	Width of Spill	Multiply by factor	Equals flow required
	45 cm	Multiply by 91	4095 ltr/hr
	18 in	Multiply by 50	900 gal/hr

Running Filtration?
For correct pond filtration the volume of the pond should be circulated through the filter every 1–2 hours . To calculate the required flow, follow this simple formula. If you are unsure of your pond volume please refer pond volume

B	Pond Volume	Divide by factor	Equals flow required
	______ ltres	Divide by 1.5	________ lt/hr
	______ gallons	Divide by 1.5	_______ gal/hr

**Example**
B	Pond Volume	Divide by factor	Equals flow required
	5460 ltr	Divide by 1.5	3640 ltr/hr
	1200 gal	Divide by 1.5	800 gal/hr

Should you decide to have a filter and a waterfall, it would be normal to position the filter so it flows into the waterfall, allowing the same water to be used for both purposes. Therefore, the flow from the pump will need to be the larger of the two above flow rates, A or B.

Cont. example: From our examples above, we will presume we are running the filter into the waterfall.
We already know we need a flow rate for the waterfall of 4095 Lt. (A) and 3640 Lt. (B) for filtration. Therefore we will require a pump to push at least 4095 Lt. Please check your filter will take this flow rate and select a larger filter if necessary. If you are running the filter and waterfall separately you will require a flow rate of 4095 Lt (A) + 3640 Lt( B) equalling 7735 Lt.

Pumping Height?
Now that you have calculated the flow rate required. You need to consider how high the filter or waterfall is above the water surface (the maximum lift)

Cont. example: Assume your filter inlet is one metre above the water surface and you are running the filter into the waterfall. Thus you need a pump which will produce at least 4095 It. at a 1 metre lift.

Do you want to use the supplied fountain jet?
(Not available with all pumps). As a very general guide you will need to add the following to your already calculated flow rate.

This is a very basic guide for running a simple spray fountain directly off the top of the pump. Please seek advice for other fountain requirements.

Cont. example: If you would like to use the supplied fountain to a medium height add 910 It. to 4095 It.
Equalling a required flow rate of 5005 It. / hr at 1 metre.

Now You Have The Required Information....
Using this information simply examine the following pages to find a pump type you prefer and one which will deliver your required flow at your maximum lift. Always choose one a bit bigger than you think you need as most pumps can be turned down with no ill effect.

Next to each pump in this section you will find symbols recommending what the pump can be used for. Ensure the pump you choose will cover all your requirements.

Please note if a pump displays more than one symbol it does not necessarily mean that the pump can operate them all simultaneously.

World of Water advise that a Qualified Electrician is
consulted prior to installation of any electrical
equipment in, on or near water or ponds.

See www.niceic.org.uk