Thanks. It does seem complicated. More to figure it out, but simply (IF THIS do THAT) Logic. It could be done all in a Apex, but I like Standalone. BTW. I just tested with Float Sensors VS Calibration. To my surprise the Float Sensors are DEAD ON ACCURATE (If they don't stick from Salt Creep or whatever) I still need the pump calibration to only get an accurate DESIRED Water Volume, on the First Drain Pump. Then with Float sensors, every thing lines up on Subsequent TANKS to a 100% Perfect Water change. And the Calibrated Volumes will actually be the Safety Check ( THINGS are REVERSED compared to what I thought). What I mean is (If sensor doesn't hit, and I'm going over-TOO-MUCH on the Expected 1 Gallon Water change, then something is wrong) ALMOST DONE. GOING to Install on the Tanks and do a few tests.