I went to the local pool store yeserday to get an education about salt chlorine generators. I wanted to stick with Pentair as my other equipment is all Pentair. The guy behind the counter showed me both the IC20 and the IC40 system and then asked how big my pool was. When I told him I had a 12,000 gallon pool, he said the most I'd ever want to put in is an IC20 as the IC40 "is way too big for your pool and will throw off your pool chemistry". How is that possible? Aren't there controls to dial back the chlorine production? Isn't it always better to buy bigger than you need so it puts less stress on the components and they last longer?
Seems to me that the IC20 and IC40 aren't that much different in price so I'd be more likely to get the IC40 unless there's a specific reason not to.