One thing i haven't seen posted yet.
I have a float sensor inside my water proof cabinent along with a self priming emergency sunk pump. 3 leak sensors, one inside the cabinent and 2 outside. When the first leack detector inside the cabinent detects water it shuts down anything that could be leaking in there (reactors, ATO and main pumps), at that time the circ pumps inside the tank go into emergency mode. When the float sensor starts to rise it turns on the sunk pump and automatically pumps any accumulating water out of the stand and into the sewage drain. Of course this would also trigger a series of texts and emails and alarms.
I can't decide if i want to go down the auto water change route. I do 40 gallons all at once every couple weeks which removes a few % more nitrates than you get when you continuously change small amounts.