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eho72
02/04/2010, 04:28 PM
I have an American Marine Pinpoint PH probe and controller. Anyhow, the controller has been working great in my Calcium reactor until now. The PH reading is not working properly so I bought a replacement PH probe along with the 7 and 10 calibration fluid. I've never calibrated before so I hope I am not doing this wrong. The instruction from American Marine is below. I started with the 7 solution and adjusted the ph just fine. My problem is with the #10 solution. That is suppose to be adjusted using the slope. However, when I put the end of the probe in the calibration fluid, it doesn't move past 7 very much. I can't get it to 10. I cleaned the probe when moving between the fluids. What am I missing here? My old probe has same issue when checking the calibration. Anyone has an idea or do I just have a bad probe send to me?

1. Immerse the tip (bottom 1 inch) of the electrode into the pH 7 calibration fluid. It is important to use the pH 7 solution first. Be sure that the tip of the probe is fully immersed in the calibration fluid for a stable and reliable result.
2. Keeping the glass bulb immersed, gently swirl the ends if the electrode in the calibration fluid until the pH reading stabilizes. If the electrode is in good condition, the reading should stabilize in a few seconds. If the electrode does not easily stabilize; this may be a sign that the electrode is in need of cleaning or should soon be replaced.
3. Adjust the CALIB screw to bring the displayed pH to about 7.00
4. Remove the electrode from the pH 7.0 calibration solution and rinse it with room temperature tap water. Gently shake the electrode to remove clinging drops of water.
5. Immerse the end of the electrode into either the low or high calibration fluid. Usually pH 4 or pH 10 is the most common. Swirl the end of the electrode in the fluid until you obtain a stable reading, then adjust the SLOPE screw until the display shows the value of your calibration fluid (typically 4.00 or 10.00).
6. Again, rinse the electrode with room temperature tap water and shake of any clinging drops.
7. Re-immerse the electrode in the pH 7 calibration solution and now repeat steps 6–7–8 until the display shows 7.00 in the pH 7 fluid and 4.00 or 10.00 in the other calibration fluid that you have selected.
8. Rinse the electrode and return it to service in your system. Remember that the sensitive glass bulb of the electrode must not be allowed to dry out. Use the clear plastic cap filled with storage fluid or pH 4 calibration fluid when not in use.