A great majority of the incidents of wrinkling that have been reported to us, have occurred in commercial or semi-commercial installations which are, more often than not, indoor pools.

These pools carry a high bather load and operators apply chlorine or bromine sanitizers at high levels as insurance against sanitation problems and in response to health department requirements. Severe bleaching of the liner is evident with chlorinated pools, confirming high chlorine concentration over long periods.

The root cause of wrinkle development has proven to be excessive chlorine or bromine levels, causing ongoing absorption of water and dimensional growth of liners. Refer to Technical Bulletin #10.

Recommendations

1. Do not supply unreinforced vinyl pool liners for commercial applications as operation of these pools at or below the maximum recommended sanitizer levels does not appear to be feasible.
   
   
2. The best material for commercial installations is reinforced triple ply PVC pool liner sheeting. The scrim reinforcement provides exceptional dimensional stability, preventing the possibility of wrinkle formation.
   
   
3. The situation with indoor residential pools is less clear. Cases of wrinkling have been reported, but not to the same extent as commercial pools. Factors that can present problems here are the lack of stabilization with cyanuric acid and high bromine levels which present very little, if any, odour and no bleaching. Bromine will also erode total alkalinity levels, resulting in greater pH swings.

Before discontinuing the supply of regular liners for indoor residential pools, a survey of past installations is recommended to determine the extent of the problem.