Water Change System Issue With ATO

[wiselyy73]

Planning to set up a water change system with Apex DOS to change 5 gallon of water each week. I am using a Tunze for ATO now. The question is during the Apex DOS withdraws water from the sump each night the Tunze fills up the water will RODI before the DOS fills with saltwater. If I schedule to turn off the Tunze during that time the DOS does fine but when I turn back on the Tunze it fills with the RODI no matter what.

How can the water change process work and maintain the water level without the Tunze on and off?

 

[glb]

I’d check your programming. So the DOS does both the removal and addition of water before the Tunze comes back on?

 

[wiselyy73]

You mean add and remove at the same time?

 

[Mark Bianco]

In theory the dos pumps should add and remove the same amount of water at the same time and your water level should never change and you could leave the Ato on at all times. However if the pumps go out of calibration or one fails there could be a problem. Most people turn off the Ato for this reason when doing a water change. Whenever you restore power to a Tunze Ato it test itself then will pump water for a few seconds regardless. That amount is very small and shouldn't effect anything. If you are first dumping out the old then adding fresh that works too just adds to the time needed to do the water change.