Pools and spas require ongoing protection from their major pollutant – swimmers

Bacteria will grow in any untreated body of water. Swimmers are the primary source along with top up water, leaves, grass and dust. Be aware that a large dog contributes twenty times as much as a human.

Bacteria is a serious health risk and needs to be killed quickly and effectively. Adding a sanitiser to the water at recommended levels will do just that.

Dead bacteria is removed by the filter and the residual sanitiser left in the water will kill any new bacteria. Most bacteria will be killed when exposed to residual sanitiser, provided recommended levels are maintained.

Regular water testing and adding the required amount of sanitiser will maintain the correct residual level. It is recommended to test water weekly or prior to using your pool or spa.


Chlorine is available in granular, liquid, or tablet form and can be stabilised or unstabilised. It can also be generated by a salt-water chlorinator. Each form has individual features and benefits. 

Granular chlorine is convenient, easy to store and relatively cheap, but cannot be dosed automatically. Liquid chlorine can be dosed automatically, but is bulky, and has a limited shelf life due to loss of strength over time. All work effectively, so consult your SPASA Victoria Pool Shop Member for expert advice.

Safety Note: Never mix chemicals - even different types of chlorine - as fire or explosion may result.


Salt chlorinators make chlorine, and come in different sizes to suit different pools, so select one that is able to produce sufficient chlorine for your needs. Even then, you may still need to add extra chlorine from time to time to maintain a satisfactory residual level.


For people who have developed an intolerance to chlorine, or who live with Asthma, there are sanitisers that do not contain chlorine and that are registered by the Australian registration authority. Further details can be found at www.apvma.gov.au. These products include Biaguanide, Hydrogen Peroxide and Hydrogen Peroxide with Silver Nitrate (the latter two are liquids and can be automatically dosed). The residual on Hydrogen Peroxide based products is several days.


Stabiliser (Isocyanuric Acid) is a chemical added to pool water to reduce the loss of chlorine due to the sun’s UV rays. Stabiliser can also be added manually to the pool, or in stabilised chlorine. Check the level of stabiliser in the water periodically. Stabiliser is not consumed like other chemicals in the pool, so it can build up to levels high enough to inhibit the effectiveness of the chlorine. 

Stabiliser is not required with chlorine-free sanitisers.


A strong chlorine smell doesn’t mean too much chlorine, it may mean too little. Ammonia can produce chloramines and these produce odour, sore eyes and itchy skin. To remove them, add a boost of superchlorination, but always consult your authorised SPASA Victoria Pool Shop first.


Heated pools and spas require more sanitiser than non-heated pools because sanitisers are consumed more quickly in hot water.

Alternative methods of sanitising pools and spas are available and are covered in Fact Sheets 8 and 9. Always consult your local SPASA Victoria members for expert advice on all pool and spa chemicals.

Download Fact Sheet 6 - Sanitisers