Probably the most important component of your pool is the pump.

It's important to have the pool water turning over at the correct volume, not only for the health of the pool, but also for your power consumption.

A pool of 40-50,000 litres will cost around \$0.25 and \$0.55 per hour that you run your pump - around \$650 - \$1000 per year.

A single speed pump will cost you less upfront and do a reliable job. However a variable speed pump will save you \$\$ off your power bill.

So what size do you need?

1.  You need to know the volume of your pool.  This is measured in litres, and calculated as follows:

Length of Pool  x  Width of Pool  x  Average Depth of Pool

For example:

Length = 10m

Width = 4m

Average Depth = 1.4m

10 x 4 x 1.4 = 56 - multiply this by 1,000 = 56,000 Litres

2.  Now you need to know the flow rate.  This is measured in litres per minute, and using the pool volume above, and the turnover time.  Turnover time means how long it will take for the entire pool water content to go through the pump system.  We need to work on achieving this in 4 hours for an indoor pool and 6 hours for an outdoor pool.

So, if we need to turn the pool water over in 4 hours this is 240 minutes, or 6 hours = 360 minutes.

We take the pool volume at 56,000 litres, and divide it by 240 minutes = 230

We need a flow rate of 230 litres per minute for an indoor pool of 56,000L.

3.  We now need to know the Total Dynamic Head in metres, which is how far the pump needs to push the water around the pool.  Most inground pools are around 15m and above ground pools are usually around 9m.  These are fairly safe measurements to use.

So our 56,000L indoor, inground pool pump needs to achieve 230 litres per minute  at 15m head.

We need to look at the middle of the pump curve on the graph to find this intersection and that will be the right pump for us.