The pH probe is used to control the pH of the reactor and not the tank. However, the reading of 34.2 can't be right.
First, let me explain how a pH controller works. In order for the reactor media to melt, you must maintain a low pH. This is done by injecting CO2 into your reactor. Say that the media you're using melts at 6.3. You set your controller for 6.3. You plug your solenoid from the CO2 tank into the controller(here the DC or X10 unit). When the pH rises above 6.3 the controller turns on the outlet to the solenoid and in goes the CO2, dropping your pH. When the pH reaches 6.3, the controller turns the outlet off again, and the solenoid stops injecting CO2 into the reactor. When the pH rises the same thing happens again.
As to the reading from the pH probe. Did you calibrate the probe when you attached it? Probes need calilbrated on the first use, and at least once a month, though manufacturers reccomend every 2 weeks. You have to use a fresh packet of calibration fluid each time, as the fluid begins to change pH as soon as it's opened. I keep half a dozen of the 7 and 10 fluid on hand at all times since calibration is a common occurence. If the probe was calibrated correctly, you might want to make sure that there's no electrical interference. You could check that by moving the controller into another room, and see if you get the same reading. Sometimes soaking the probe in RO water overnight will remove and residue, and that will clear up the problem. If you've checked all these things, let us know. We'll get you in touch with Neptune, and they'll cover the warranty on your probe.
