mdvistnes
11/19/2008, 09:26 PM
Hello - I have a question on a lab grade pH probe calibration for a salt water reef tank using the AC Pro III. I recently ordered one from marine depot and tried with 3 different sets of new calibration fluid (7 and 10) to calibrate it, and it calibrates low. I'm replacing a 3 year old probe that consistently read pH of the tank at 8.1 to 8.2. A test kit currently confirms these values. When I calibrate the new probe my readings are 7.7 - 7.85 range no matter what I do. I put the temp probe in the same fluid to calibrate it as instructed. I called MD and they said send the probe back and they will ship a new one. So is there anything I should do differently? Does it matter if I decant the calibration fluid into a glass beaker to calibrate it or should I leave it in the foil packet? I let it settle until the level is stable. The temp correction on the AC III is set to on and pH is set to on when I calibrate it. Am I missing something? Thanks!