I'm pretty much in Agreement with Tom, and VaughnH. I'd add that a PH controller is only as accurate as the guy that calibrated it. (Ask me how I know) That may seem like a no brainer, but many times technology only provides the "Illusion" of control ! ;^) A solenoid on a timer is more than sufficient. A controller is just as likely to be another weak link in the chain. There's no substitute for conscientious maintenance. A PH Controller isn't an insurance policy. Found that out the hard way !!! ;^)