How do you calibrate a PH meter?

[Thinslis]

I bought a used Pinpoint PH meter and it is not reading correctly so I want to try to calibrate the probe before I replace it. However the meter did not come with instructions. I have a packet of PH 10 and PH 7 calabration fluid, how do I go about calibrating?

Thanks,

[USC-fan]

All calibration fluids should be room temperature 68°– 86°F (20°– 30°C)

1. With monitor turned "ON", place the end of the pH probe into calibration fluid #7.00 Using a miniature screwdriver, turn screw labeled #7 on the front panel of the meter (see diagram) until display reaches 7.00 exactly.
2. Rinse probe in room temperature tapwater.
3. Place pH probe into calibration fluid #4.00 (or #10.00). Wait several seconds for reading to stabilize. If adjustment is necessary, turn screw labeled 4, 10 on the front panel of the meter (see diagram) until the reading reaches 4.00 (or 10.00) exactly.
4. RECALIBRATE with #7.00 calibration fluid as step 1.
5. Rinse probe with fresh room temperature water.
6. RECALIBRATE with #4.00 (or 10.00) calibration fluid as step 3.

Continue the calibration between both fluids. The two-point calibration is fully complete when monitor will display both calibration fluids correctly without any adjustment necessary.


here is the rest of the manual. http://www.americanmarineusa.com/phmonitor.html

[Thinslis]

Thanks, that probe needs replaced if you can't get it to read properly with the fluids and adjustments?

[USC-fan]

yep, and or if it been dry out it needs to be replaced.

"Keep the sensing surface of the probe WET at all times. If the probe is to be transported or stored, the plastic cap must be filled with storage solution (4.00 calibration fluid + potassium chloride crystals) or 4.00 calibration fluid prior to being installed onto the probe."

[Thinslis]

That sucks, the cap was dry when it was shipped to me =( lame.