My experience was a bit different than Evan's. I increased my CYA from 30 to 70 ppm and did not see a rise in CL residual for the same settings so I was unable to turn down my SWG. Our different results could be due to the size of pool, UV exposure or other factors. So I think it really depends on the conditions of the pool as to need of high CYA.

One thing I found useful during my expermental rise with CYA was to calculate how much CL was going into the pool per day. I know how to do it for the Goldline SWG but not sure for the poolpilot. Sean should know. Anyway, I found I was putting in 2 ppm per day and my residual was at 2 ppm. So based on that, I probably should not have bothered adding more CYA but I wanted to try it anyway. So if your residual is much less than what you are putting in per day, then I would say you probably need more CYA.