Mine is an inground pool with NO overflow. If the water gets too high, it just runs over the flagstone coping and runs off into the yard, which I prefer anyways, VS sending perfectly fine water down the drain to the sewer. I am OK with no overflow.
My brother in law had a saltwater pool for a few years and found that it really was hard on his stonework and his pool furniture. He now chlorinates again and swears that he less wear on his stone and his aluminum pool area furniture. I am just fine with the Chlorine setup that I have now. Its really easy and automatic with the opensprinkler controlling my chrloination.
Now, for the fill…I am going to gather some data. I picked a place inside my skimmer yesterday, and made a mark with a sharpie. If I run my tape measure down to the top of the skimmer housing, I can measure the depth at the same place each time. I plan to make a table in a few days, that will record the pool depth and also some weather parameters. I thought about recording the high temp, whether its sunny or windy… But a simpler way may be to record the weather adjustment that is offered up by opensprinkler for that day. I have not yet paid much attention to that side of things, but it would be handiest to arrive at a correlation between the opensprinkler weather adjustment data and the evap rate of the pool. For filling, it will be a simple matter to run the fill valve and see how many minutes it takes to raise the pool 1/4″. That’s the easy part.