I have a 75 gallon tank, CO2 injected, 220 watts of cpl, JBJ regulator, Ebo Jagger heater, and Milwaukee pH controller. I test my pH of my water everyday with American Pharmaceuticals pH test. I noticed that my pH prob would be off. It would read 6.8 and the waters pH would be around 7.6 via American Pharmaceutical pH test. So I would calibrate my prob and in a day sometimes a couple of days the prob would be off again. It would read 6.8 and the waters pH would test 7.6. I changed test kits but still got the same reading. I called Milwaukee and they told me to send it in. While the pH prob was in the shop getting fixed I attached a Pin point controller to the tank. For a couple of weeks the prob was dead on with the test kits. Then the last week it was off. the pin point read 6.8 and the water was 7.6. Does anybody have an idea why the crazy readings. Could it be to many electrical wires?