CYA evaporation

[jmmctighe]

I know the only way to lower CYA is to drain and fill, or partial drain and fill. But when the water evaporates from the sun, does the CYA evaporate with it or does it remain in the water thus increasing the ratio of CYA to water volume?
Also, what water condition does too much CYA produce? I'm at 65 now, pushing the upper limit.

[waterbear]

CYa does not evaporate, it will concentrate in the water as water evaporates (the same as any other ionic solid in the water, i.e. calcium, salt, etc.).
HIgher CYA just means you have to run higher FC to compensate (to keep enough 'active' chlorine in the water and not bound up with the CYA as a chlorinated isocyanurate) unless you decide to do a partial drain and refill.