Static: I'm using a PLC like device to drive SSRelays like
here, simple and clean to switch heaters.
Kwirky: Queried American Marine about the output of their probe
e-mail reply AMI
"After proper calibration the probe will generate 59 mV per each unit of positive pH and the opposite will be negative mV. Example pH 7.0= 0 mV; a ph of 8.0=59mV a pH of 6.5= -30mV Good Luck...Lou Dell/AMI"