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Recent legislative changes in some Australian states have opened the way for the use of stabilised chlorines in commercial indoor pools. These changes were brought about, in part, by a collection of scientific papers forwarded to all State Health Departments debunking the "chlorine lock" myth. The data pack was provided in support of SpaGuard Spa Lite, which was subsequently approved by the National Registration Authority for use in indoor spas and hot tubs. Unfortunately, at the time this Technical Information Bulletin was prepared, no State Health Department had made a move to raise the level of cyanuric acid (CYA) permissible in a commercial pool (either indoor or outdoor) from its present 100-ppm limit. As such, Health Department officials are still instructed to order the partial draining of a commercial pool or spa where the stabiliser level exceeds this limit.

To assist the owners and operators of such pools or spas, the Tables below provide an estimation of the time taken for CYA levels to reach 100 ppm from fresh fill using BioGuard and SpaGuard products. It must be stressed that the following Table gives theoretical CYA levels at approximately 25°C and that CYA levels will drop over time due to losses from splashout and decomposition, so these estimates could well be conservative. Remember, too, that the 100-ppm CYA limit applies to commercial units only and that levels of up to 400 ppm have been legislated by many US states.


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.