After months of thinking about it, and alot of research on simple, and complicated ATO's, I built my own I felt would work best on my set up. I 'T'd the DI line of of my RO/Di to a float valve I installed in my sump. Fot me, this was the simplest, and would work the best, for under $20. I have a shut off valve in the feed line also. I ran a 1/4 inch line from my RO/DI under my kitchen sink, under the floor, thru the ceiling of my basement, back up thru the floor behind my DT, to a nice inexpensive float valve in my sump. Works great! NO more adding ~2 gallons /day by hand!