How a Swimming Pool Works

Understanding how your pool system works will enable you to troubleshoot potential problems with more ease and build the foundations for learning about each individual piece of equipment, such as a pump, filter or heater.

So, how do they work?

Pool water moves in a continuous cycle driven by the pump. Equipped with an electric motor, the pump has an impeller that drives water through the skimmers (found at the top of a pool) and the sumps (found at the bottom of a pool) take it to the filter. The clean, filtered water is then piped through the return nozzles (a series of small valves placed around the pool).

Diagram of a swimming pools inner workings.

To prevent the pump from becoming clogged, the water first passes through a basket-like pre-filter made from plastic. This is in order to catch leaves and other debris that are large enough to block the system or the pump.

From the pump, the water then reaches the filtration system, where most small particles of dirt are removed. The water passes through a filter bed of fine sand or glass particles. These particles trap even very fine particles of dirt but allow water to come out the other side. This sparkling clean filtered water then re-enters the pool through the outlet pipe. However, over time the filter bed will accumulate increasing levels of dirt, so will need replacing every one or two years.

The filtration system removes debris that bacteria and algae feed on. This is paired with sanitisation - the other core function of your pool system - to keep your pool clean and attractive. Sanitisation directly destroys the bacteria and algae that enter your pool. An automatic and cost-effective sanitiser is to install a chlorinator, as in the diagram. Chlorinators continuously measure and dose the correct amount of chlorine into your pool, keeping your pool safe, healthy and looking fantastic.