I use my Hydros for my auto water changes. They have a built in auto water change regimen you can use but it also has to be the ATO since it will disable the ATO during the water change. It also uses the same full sensor as the ATO in the AWC. You can either use a specific time for the drain or use an optional water level sensor to drain down to. You can choose the pumps you want to use as long as they can be controlled by turning them on and off. I use dosing pump for my pumps but the main reason for that is my fresh saltwater reservoir is in the garage and the tank is 35ft away. So the tubing is run up through the attic to and from the tank. Both pumps are also in the garage.