You can’t turn it off.
So I got the cube filled today! About 18 gallons after all the sand and rock displaced some water. Used Caribsea Aragalive Special Grade Reef.
Dosed with fritz turbo 900.
Avast ATO was super easy to set. Just set where I wanted it. Disconnected the RO tube from the switch box and let the water find it’s level in the sensor tube. Then plug the RO tube back into the control box. Done. Now if the water in the tube drops the pressure switch activates the pump and fills the tank!
Still trying to figure out how to turn the AI Prime off without just unplugging it.