I've been using pH/ORP controllers indoors for 18 years and never saw those kinds of problems. I can't even imagine how you could do that kind of damage.

Training is definitely and issue but I've not had that hard a time getting the operators to understand the difference between ORP and PPM residuals and how it's dependent on pH. Typically a two hour session about the care and feeding of controllers and test kits is enough to keep new operators from making major mistakes.

What I'm interested in here is using pH/ORP in conjunction with CYA. Because CYA sequesters part of the HOCL residual in a form that an ORP probe doesn't react to it would be vital to keep CYA levels constant. if anyone has attempted it I'd like to hear how they made out.

Personally I think such controllers are overkill for a home pool as there just isn't the bather load or the 18+ hours of constant use that public pools have to deal with. however, some folks a tech junkies and may have one fitted.