I got the floats switches and latching relay and solenoid at autotopoff .com. Its been flawless two years now. Float switch in ato on bottom for low and float on top for high. When water level drops it sends signal to solenoid to open and turns on rodi unit when it fills to top it triggers top float which in turn sends signal to close solenoid and shut off rodi. Its good for about 5 days and repeats the process avoiding constant turning on and iff RODI and tds creep