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STA POOL PLANT – HARD WATER

How Hard Is Your Water? Ensuring the correct levels of chemicals and minerals in a swimming pool is vital to keeping a pool and bathers healthy. Luke Griffiths, Qualification Development Manager (Pool Plant) at STA’s awarding organisation’ Safety Training Awards, discusses the potential issues of swimming pool water being too hard or soft here with James Dyer from Aqua Cure, who recently launched a hard water postcode check.

S

o, what do we mean by these terms, too hard or too soft, and how can each be prevented?

HARD, SOFT OR SOMEWHERE IN BETWEEN? Ideally swimming pool water should contain sufficient hardness. Soft water can be more of an issue to swimming pools but excessively hard water can also pose problems. Hard water has a high presence of dissolved minerals in the water supply, predominately magnesium and calcium. These minerals are the major contributors to scale, and excessive levels can cause damage to swimming pools, blocking pipework and injectors, as well as developing unsightly white residue or ‘scale’ left in and around pool surfaces. Water that is too soft can also create issues with the water needing to have some calcium content to avoid it becoming corrosive. If swimming pool water is too soft, the water will have corrosive tendencies and may seek to balance itself by absorbing calcium directly from the pool walls and other surfaces that contain calcium, including metal components such as heaters and railings. In the UK and Republic of Ireland, the South East of both countries generally have harder water than the West, although there are exceptions to this rule and mains water can vary not only in terms of location, but day to day in some areas depending on the water sources used by the water companies. Most water companies will provide detailed information on the characteristics of the water. Mains water should be tested prior to designing a swimming pool plant and selecting which chemicals to use; and at least monthly afterwards to ensure operators know what the properties are and allow them to adapt to any changes in characteristics. For an idea of the level of water hardness in your area, take a look online at Aqua Cure’s Water Hardness Postcode Checker and map of water hardness.

HOW DO YOU TREAT HARD WATER? Understanding the properties of the mains water allows swimming pool operators to select chemicals that complement their particular type of water. For example, once pool operators know whether their pool is supplied with hard or soft water they can make an informed decision on which disinfectant is most suitable. For pools supplied with soft water, choosing calcium hypochlorite for disinfection will increase the levels of hardness in the water and reduce the risk of corrosion. For pools supplied with very hard water, they may prefer to use sodium hypochlorite as using calcium hypochlorite can result in increased scaling of pipework. However, calcium hypochlorite can still provide excellent water quality in areas supplied with lower levels of hard water.

Understanding the properties of the mains water allows swimming pool operators to select chemicals that complement their particular type of water” www.swimmingpoolnews.co.uk 39_SPN_October_19_STA.indd 39

Hard to very hard

Medium to hard

Soft to moderately hard

In addition to understanding if mains water is hard or soft, other properties to test mains water for include free chlorine, total chlorine, combined chlorine, pH, total alkalinity and total dissolved solids (TDS). It is clear that the characteristics of mains water does have a huge impact on the chemical choices for swimming pools. Understanding the properties from the start and ongoing monitoring go a long way towards continued safe and efficient operation. As well as cost savings on chemicals, maintenance and repairs. The STA Level 3 Award in Pool Plant Operations covers in more details the various considerations and options for pools supplied with different water characteristics. The qualification has CIMSPA professional endorsement for meeting the employer-led pool plant operative professional standard, and covers all that operators need to ensure safe, clear and hygienic water practices in pools, spas and interactive water features. Aqua Cure 01704 516916 www.aquacure.co.uk Safety Training Awards 01922 645097 www.safetytrainingawards.co.uk

SPN October 2019 39 04/10/2019 17:42

Profile for Aqua Publishing Ltd

SPN (Swimming Pool News) October 2019  

Informing the pool and spa industry since 1959. Covering the UK's wet leisure market, SPN (Swimming Pool News) is the UK's longest running a...

SPN (Swimming Pool News) October 2019  

Informing the pool and spa industry since 1959. Covering the UK's wet leisure market, SPN (Swimming Pool News) is the UK's longest running a...