Conditioner problems in pool water

Pool water problem - conditioner

Conditioner (or stabilizer) is necessary in the pool water to protect chlorine from the sun's UV rays. Its chemical name is cyanuric acid (no, it's not the same as cyanide) and forms a compound with the free chlorine giving it more durability in sunshine.

Required conditioner levels

The pool water should ideally have 30 - 80 ppm conditioner if you are using chlorine. Conditioner may be added separately, but is found is many ready-to-use chlorine products so in most pools this is not necessary.

Products containing conditioner

Many commercial chlorine products include conditioner. They are as follows:

Chlorine products containing 57% conditioner by weight are:

  • Dichlor
  • SDIC
  • Sodium dichlor
  • 56% chlorine granules, 60% chlorine granules

Chlorine products containing 54% conditioner by weight are:

  • Trichlor
  • 90% chlorine tablets, sticks, granules

High conditioner levels

Swimming pools using dichlor or trichlor products may suffer from high conditioner levels due to the frequent addition of chlorine. Regular backwashing (once a week) helps to keep the conditioner level down, but pools requiring high doses of chlorine tend to reach the limit quite quickly.

Some states have ruled that the cyanuric acid level must never exceed 100ppm and public pools are closed down if and when this limit is exceeded.

Results of excess conditioner

The following problems may result in pools with a conditioner level above 80ppm:

  • cloudy, milky pool water;
  • algae (despite free chlorine levels of 3.0 ppm or more);
  • dull, lifeless water.

Reducing conditioner levels

Unfortunately, the only way to reduce the concentration of conditioner is to (partially) drain and then refill the swimming pool to bring the level to within the recommended levels of 30-80ppm.

Preventing high conditioner levels

By monitoring the level of conditioner in the swimming pool, we can prevent the level exceeding the upper limit. As the level approaches 80ppm, the continued use of cyanuric acid containing products is not advisable.

In place of these products, the following sanitizers/ oxidizers can safely be used:

  • liquid chlorine (sodium hypochlorite);
  • Lithium hypochlorite (powder);
  • Calcium hypochlorite (65% or 70% granules/ tablet chlorine);
  • non-chlorine products such as persulfates.

Note: whether cyanuric acid is carcinogenic is a much debated issue and so excessive levels in swimming pool water should be avoided until studies prove it to be safe and harmless.

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