There's a million of them out there; good, bad, etc. Eventually, pretty much all of them will have some sort of problem eventually. I'm going to try the "liquid level controller" from purely H20, which is three stainless steel sensors that work on conductivity to turn on/off a solenoid which runs the R.O. filter. Are you trying to do auto top-off for your tank or just keep a tub filled with water?