Surface Water Draw-Off System
Most of the pollution in a swimming pool will sit in the top 150mm of pool depth. Therefore, there needs to be an effective system for removing as much of this pollution as possible. There are three different types of surface water removal system:

• Deck-level
• Skimmer
• Scum trough

Which system is installed on a pool is largely down to when the pool was built. Deck-level systems are the newest type, scum trough systems are the oldest.

Outlets (or sumps)
As well as leaving the pool via the surface water draw off system, water is also leaving via the outlets (drains). In a traditional swimming pool, these outlets are usually located on the floor of the deep end and are covered with a square grill.

Strainer(s)

The pre-pump strainer is designed to trap the larger items of physical pollution before they can get into the pump itself, where it would cause damage. The strainer basket sits inside a vessel and can be removed for cleaning.

Circulation Pumps

The circulation pumps are the ‘heart’ of the circulation system. They are designed to continuously pumps water around the system at a pre-determined rate called the flow rate. In larger installations there are usually several pumps working at the same time, with additional pump(s) on standby. In smaller installations, there may only be one single pump.

Filter(s)

Filtration is a fairly simple process; water leaves the pool via the deep end outlets and the surface water draw-off system (deck-level, skimmer baskets, overflow channels etc.). It is piped to the plant room and gets directed into the top of the filter (or several filters in large pools), passes through the filter media (usually sand) where all the contaminants and pollution are trapped and the pool water comes out of the bottom and continues through the remaining components of the pool plant system.

Heat Exchanger

The heat exchanger is usually the final component that the pool water is circulated through before it is returned to the swimming pool. There are two types of heat exchanger used in pool plant. They are the coil heat exchanger and the plate heat exchanger. The plate heat exchanger is the newer type and is more efficient at heat exchange than the older coil heat exchanger, although the principles on which they work are very similar.

Automatic Monitoring and Dosing

Automatic monitoring and dosing of water treatment chemicals should be the norm in a commercial swimming pool/ spa. Hand-dosing chemicals should only be undertaken in exceptional circumstances, after a thorough and robust risk assessment has been conducted, and only by people trained and competent to do so. Chemical dosing should be continuous, 24 hours a day.  The automatic dosing system should be backed up by regular monitoring and verification.