copper sulphate to combat cya

Hi All, I¨m new to pool forum so please go gently with me.

I´ve been cleaning pools in Spain for a few years and have dificulty convincing customers to part drain their pools to control cya levels. In fact if I insisted on it I wouldn´t have many customers left due to the cost of water.

I know a number of pool cleaners and none of them dilute pools and rely on copper sulphate (in addition to triclor) to compensate for the high level of cya. I used to shock regularly with sodium hypo and experimented with bromine but a little cuso4 does a much better job controlling algae in the summer months.

I explain to customers the problem of cya and copper staining and almost without exception they opt for copper rather than wasting water. Only a few are willing to spend on a swg to resolve the problem.

Are others faced with the same problem of being unable to dilute pool water to the extent needed to control cya?