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(This is a Technical Bulletin circulated by Canadian General Tower Limited, April 12, 1989)


Wrinkles will develop if an installed vinyl liner is slightly oversized. However, the purpose of this bulletin is to discuss wrinkling that may occur in a properly sized liner.


A laboratory testing program to study the effect of pH and cyanuric acid stabiliser levels on vinyl swimming pool liner materials was conducted by Union Carbide Corp and FMC Corp in 1969. The results of their experiments have been verified by other labs.


The most significant conclusions of the above study were:

1. Low pH is the major cause of dimensional instability resulting in wrinkling. Test samples immersed in 6.0

pH solutions showed weight gains much higher than samples immersed in 8.0 pH solutions. Dimensions of the samples also increased in proportion to weight gains.

2. Acidic chlorinating chemicals such as trichloroisocyanuric acid tend to lower pH unless counteracted by neutralising agents. Therefore, monitoring of pH is more critical when using acidic sanitizers.

3. Cyanuric acid stabiliser levels of 50 ppm were shown to reduce the magnitudes of weight and dimensional increases at both 6.0 and 8.0 pH. Therefore, cyanuric acid stabiliser appears to have the ability to provide some insurance against the detrimental affect of unanticipated pH fluctuation.


Incidents of wrinkling that have been reported to us, have almost always occurred in situations where cyanuric acid usage was deemed to be unnecessary, such as indoor pools or brominated pools. Therefore, it is recommended that all vinyl lined pools be routinely stabilised with cyanuric acid, including indoor as well as brominated pools.


Footnote: Unfortunately, here in Australia you CANNOT use stabiliser in an indoor pool as per Australian Standards 1989, except in Victoria (as of 2001) and Tasmania.


The above information is supplied by Bio-Lab and represents its best interpretation of available technical information at the time of preparation. The sole purpose is to supply factual information to Bio-Lab customers. It is not to be taken out of context nor used as support for any other claim not made herein.