The most important technical consideration when choosing pumps is their suitability to the system.

Before talking about pumps, there are two terms that need to be understood clearly: head and volume.

Head is the vertical distance between the water level you are trying to pump from and the water level you are trying to pump to. Head is completely independent of the depth of the water bodies involved. When calculating which pump to install, it is essential to also take into account total dynamic head, which includes the amount of friction in the pipes. Friction is calculated by the diameter of the pipes, the bends and elbows, the length of the pipeline, and the internal surface texture of the pipe.

Volume is the amount of water a pump can move at a given head.

When investigating pumps, always ask for the pump performance curve. This is a graph that plots head against volume for all pumps and should be provided to you by the pump stockist.

The way pumps deliver water is directly related to the design of the impeller and how it sits in the impeller chamber. High head/low volume pumps have impellers that operate very close to the edge of the impellor chamber. This allows very little water to slip past the impeller and produces a lot of pressure, which translates into high head.

Low head/high volume pumps have more of a gap between the impeller and the wall of the impellor chamber, creating less friction and thus more volume, but low pressure and thus low head.

Traditional pools need a high head pumps to push algae and bacteria killed by chlorine, through the fine sand in a pressurised filter. This means that swimming pool pumps consume a lot of electricity while producing comparatively little flow volume.

Natural pools do not need high head pumps, but rather need the water to trickle slowly through the gravel bed and plant roots. So pumps that have low electricity consumption while delivering high volumes are preferable. Usually, submersible pumps are installed in Natural Pools because they are silent and generally more energy efficient.

The rule of thumb with natural pools is to circulate the entire volume approximately 4 times a day.