I use a very similar setup. I recently encountered a fatal flaw however. Two solenoids froze in the on position one weekend while nobody was in the office. Monday AM the office was flooded and 95% of the tank was dead.
Now I use a timer on each solenoid so that they can only be activated a total of 2 hours per day and I replaced all solenoids and float switches. Both float switches must read low water for the power to the timers to be activated. There are multiple solenoids and I check them from time to time by manually turing them on and off by turning the timers on and off. Water is added slowly of course, but nearly 72 hours of unchecked flow is a disaster.