I have a pool pilot dig with a rc42 cell & 32300 gals of
water. I'm trying to get the per cent purification set. It is
on power setting 1 and I have it set at 65% and it still is
not keeping up. When do you know when to switch to the
next higher power setting.

Fc=4
Cc=0
Ph=7.5
Ta=110
Cya=90

I think you should start on power level two and at least 50%. And take it from there. I suspect you may even have to go up from that but you have a larger cell than me so I don't know how much more it puts out then my SC-36. I would rather error on the side of too much FC than not enough. All the bad stuff happens from not enough.

agreed. I'd usually say if it's at 75% or higher, increase the cell power level. If it's 25% or lower, decrease it.