If you don't mind some more input ...
That ATO unit seems kinda pricey considering it only comes with float switches and no pump
I own no shares in Tunze
but I'd say they don't compare
The Osmolator uses 1 float for backup and a sensor eye for the pump trigger. Plus it comes with a pump, and the latest models have an adjustment pot ( internal ) that controls the DC output to the 12v pump
PM me if you want some user feedback/install tips