A Guide to Water Balance For Swimming Pool and Maintenanance

by Pool Builders on 04-23-2009 in Articles

Remember: Maintaining water balance is critical to ensuring the effective action of your pool chemicals, it should be checked regularly and, certainly, every time you top up or refill your pool or spa. Before adding swimming pool chemical treatments it is important that you read and familiarise yourself with the workings of your spa / pool and support equipment. Good water circulation and filtration are essential to achieving a safe and clear bathing environment. The first step is to ensure good water balance, which will create the right conditions for bather comfort, chemical efficiency and equipment protection. The main criteria affecting water balance are calcium hardness, pH and Total Alkalinity.
Calcium hardness

Hardness is the measurement of calcium salts in the swimming pool or spa water and this will vary depending where you live. Low calcium hardness levels (soft water) can lead to corrosion of the materials of construction. High calcium hardness levels (hard water) often leads to the formation of scale in pipe work and equipment.

  • Ideal calcium hardness levels are between 100 to 200 ppm (mg/l).
  • When the level is below 75 ppm (mg/l), apply Hardness Plus products
  • When the level exceeds 200 ppm (mg/l), apply a Scale Inhibitor


The pH scale has a range of 1 - 14 with 1 being very acidic, 7 being neutral and 14 being very alkaline. It is essential to maintain spa water within the 7.2 - 7.6 range which, being slightly alkaline, will protect equipment from corrosion and provide the optimum conditions for bather comfort and sanitiser efficiency.

  • Ideal pH level for spas is between 7.2 - 7.6.
  • If the pH is below 7.2 use pH Plus products
  • If pH levels exceed 7.6 use pH Minus products

Note: pH can be difficult to control in spas as the system water turns over quickly, is highly agitated and operates at higher temperature than swimming pools. All these factors will cause the pH to fluctuate.

As a consequence rises in pH will lead to the performance of chlorine (HOCl) sanitisers to drop dramatically. Much higher doses of chlorine sanitiser will be required. This can be avoided by using Bromine Tablets, Bromine (HOBr) is a highly effective sanitiser, and it is stable over a much wider pH range than chlorine treatments. It is also less volatile than chlorine and will remain in the spa for a longer period reducing chemical usage and ensuring hygienic conditions prevail.

Total Alkalinity

Total Alkalinity (TA) acts as a buffer to prevent pH change. If TA levels are too low the pH will fluctuate widely.

High levels of TA will not only affect water clarity, but also make pH adjustments extremely difficult.

  • Ideal TA is 100 ppm (mg/l) When TA is below 80mg/l use Alkalinity Plus
  • When TA is above 140mg/l use pH Minus to reduce it

Test Strips/kits are available for you to test the water regularly.

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