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Pool Water Chemistry

Why a correct pool water balance is important

Correctly balanced water means the chemical demands have been met, however, if chemical levels are too low the water will aggressively seek the elements it needs by attacking the pool's lining/surface and equipment. This can lead to severe corrosion problems if not corrected. Not only that, improperly treated or untreated water can be a serious health threat to bathers. On the other hand, high chemical levels may lead to the formation of scale on the pool surface and accessories and premature destruction of equipment.

Incorrectly balanced water can cause expensive damage and inhibit the sanitizing process. In simple terms, pool owners should balance the following variables:

  • pH - Potential Hydrogen
  • TA - Total Alkalinity
  • Calcium Hardness
  • Stabiliser

pH is a measure of how acidic or alkaline the water is. The pH scale ranges from 0 to 14, with 7.0 being neutral. Values below 7.0 are acidic, and value above 7.0 is alkaline. Australian standard 3633 define the range as 7.0 to 7.8 and the recommended range of 7.2 to 7.6 ( or 7.0 to 7.6 for fiberglass pools). Incorrect pH levels can have to follow effects;

  • Cause swimmer discomfort - Particularly irritation to the eyes
  • Interference with the action of your pool sanitizer
  • Promote water cloudiness & scale formation
  • It is important to note that a saltwater chlorinator slowly raises the Ph of the water; meaning acid will need to be added regularly to keep pH in range.

Total Alkalinity (TA), is the measure of Alkaline salts bi-carbonates, carbonates and hydroxides in your water. The Australian standard 3633 recommends a range of between 60 to 200ppm. Always ask your pool builder or pool shop for advice on the correct level for your type of pool. Low TA can lead to erosion of the surface of concrete or painted pools. For people swimming in water with low TA, the water can feel unpleasant causing mild skin irritation and itchiness. It will also cause unstable Ph levels with small additions of other chemicals resulting in major shifts in pH. This is sometimes known as “pH bounce”. Total Alkalinity can be changed in the following ways;

Topping up your pool will change the Total Alkalinity depending on the TA of the Top-up Water
Adding Buffer (bi-carb soda) RAISES the Total Alkalinity
Adding acid to your pool to lower pH will also LOWER Total Alkalinity

Calcium Hardness is the measure of dissolved calcium in your pool water. The recommended range is 80 to 500ppm according to Australian standard 3633. Total Alkalinity and Calcium Hardness need to be brought into balance. If the correct balance is not maintained, low levels of CH causes corrosion to the pool surfaces and equipment. High levels will lead to scale formation. If you are using calcium hypochlorite (granular chlorine) to sanitize your pool, this will raise calcium hardness levels, which will require more frequent testing and adjustment.

Chlorine stabilizer (isocyanuric acid) should be added to the pool and maintained at approx 30-60ppm to reduce chlorine loss due to UV rays. If the stabilizer level is too low, rapid depletion of free chlorine will occur. If you are using Stabilised granular chlorine products such as (Sodium Dichlor or Trichlor tablets) to sanitize your pool, this will raise stabilizer levels, which will require more frequent testing and monitoring.

JC Pool Services is a Zodiac Products & Chemicals Titanium Dealer. For more information regarding the Zodiac range or any other brands of pool chemicals call 1300 117 665 alternatively you can contact us by email or see us in store at one of our three locations.