I was planning on doing the same thing as you this week but realized that I didn't need the DOS after realizing that the RO line that fills my RO tank in my mixing room is pressurized. So I put a 1/4" T fitting (i.e. a splitter) in the RO line just after my RODI filter and just before my RO mixing room tank, then ran an RO line from the T fitting 50 feet directly to my ATO. Then I put a Neptune Solenoid at the end of that pressurized RO line, right before it enters my ATO. I already had a Neptune water level sensor in my ATO and programed my Apex so it opens and closes the Neptune solenoid based on high and low water levels in my ATO. i.e. If the ATO water level is below 10" then turn the solenoid on, and if the water level is above 15" then turn it off. Its working amazing for me and saved me having to run the 50' USB line to my mixing station and eliminated the need to use the DOS at all. I put some redundancy in my setup to ensure no overflows happen as well, just to be safe, but now can use my DOS for, um, dosing!