[Ulmo]

My ATO:
Apex
breakout box
digital aquatics float switch
Tom's aqualifter pump

The program turns on the ATO every ~4 hours and replaces what has evaporated. It typically runs for 5-10 minutes, with a check for the return pump and salinity. Worst case scenario my entire reservoir slowly empties into my sump causing 3 ppm salinity drop. No flood, my sump is big enough.

[SumpATO_A8] (virtual outlet for switch)
Fallback OFF
Set OFF
If Sw1 OPEN Then ON
Defer 001:00 Then ON
Min Time 240:00 Then OFF
If Outlet RTNPUMP_4_2 = OFF Then OFF
If Condx5 < 33.0 Then OFF

[ATO_4_4] (aqualifter outlet)
Fallback OFF
Set OFF
If Outlet SumpATO_A8 = ON Then ON