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Water Volumes

Pump & Pool Sizing

To Calculate the Water Volume in a Pool:- Calculate the cubic area of upper area over shelf level and add to volume of the remaining area between the shelf level and the bottom of the pool.

To do this:-

Measure the overall average width and then measure the overall average length of the pool surface. Multiply these two values together. This gives you an approximate surface area of your pool.
Measure the water depth from the surface down to the first shelf level. Multiply your surface area value by this figure to give you the cubic volume of the upper portion of the pool.
Repeat parts 1 and 2 but take the area to the inner edge of the shelf. The depth for the second calculation will be the overall depth of the pool water to the bottom less the depth from the water surface to the first shelf level.
Add the resulting two volumes together to give you the approximate pool volume in cubic feet or cubic metres. Make sure that you used the same units of linear measurement for all the sizes!
To find the volume of water in litres or gallons multiply your final cubic volume by the appropriate conversion factor.

Conversions: -

35.31 Cu ft = 1 Cu metre.

1 Cu ft = 6 gallons of water.

1 Cu Metre = 212 gallons or 966 Litres

1 gallon = 4.56 litres

Or (x) litres x 0.22 = (y) gallons

Pump Sizing: - Your Pump should be capable of pumping at least 50% of the total pool volume through the filter system every hour. In practise you do not really want to move this volume of water and you should aim for nearer a third 33% each hour otherwise you will be creating too much water movement. Your filter may also work more efficiently at slightly lower flow rates than the manufacturer recommends.

Allow additional pumping power and capacity if you are thinking of including for a waterfall &/or a fountain feature. You will also need to allow for pressure loss and flow requirements caused by bends in the pipework and also the distance and height that the water is to be pumped.

Head = The Vertical distance between water surface & the outlet at the top of the water feature. The higher the head the lower the water output. Most pumps specify the maximum head that they are able to pump the water up to and also the resulting reduced flow rates that it causes.

Width of Water Falls: - A flow of water of 1365 Litres (300 Gal.) per hour will give you a thin continuous flow of water over an opening lip that is 150mm wide.

For a wider opening you must add 1365 Litres (300 gal.) per hour per additional 150mm (6”) width of waterfall. This should be increased or decreased pro -rata to accommodate your designed feature. We always prefer to oversize the pump specification and then use a flow reducing valve in-line if we find the flow is too strong for the falls and / or the filter and Ultra Violet Light filter.

Add at least 30% for an additional fountain.

Add at least 25% for pipework friction. If you are pumping more than about 2.4m (8 feet) then we would increase this to 30% or more.

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