That's the really funny part, as much as I hate internal skimmers they are in essence self regulating to a certain degree. When the overflows happens the water level in the sump naturally drops and as a result the skimmer starts shutting itself down well before any concern about running the sump dry.
Part two is the ATO then as you indicated, it's the Grigor approach limiting via both water level and time. Float switches for water level and Apex limits the pump to only run 3x times a day for 5 minute intervals and a 1 minute min run time. Yes, over time the system tends to lean out. Time is measured in 4-6 months for a .01-.03 salinity drop. I check salinity once in a blue moon and etop off with a load of salt water or two. My AWC tends to run a little salty (I never test that batches of salt water I mix up) which I think tends to balance things out.
Part two is the ATO then as you indicated, it's the Grigor approach limiting via both water level and time. Float switches for water level and Apex limits the pump to only run 3x times a day for 5 minute intervals and a 1 minute min run time. Yes, over time the system tends to lean out. Time is measured in 4-6 months for a .01-.03 salinity drop. I check salinity once in a blue moon and etop off with a load of salt water or two. My AWC tends to run a little salty (I never test that batches of salt water I mix up) which I think tends to balance things out.
