pH/Conductivity Meter
Tech Support

Q:  When are the pH 4.0 and pH 7.0 solutions used?

A: The pH 4.0 and pH 7.0 calibrating solutions are used to make sure the pH Meter is properly calibrated. The solutions should be stored at room temperature. Set the pH/Conductivity Meter to pH mode. Insert the pH meter into the 7.0 solution and calibrate to 7.0. Rinse the electrode in distilled water. Insert into the 4.0 solution and calibrate to 4.0. Rinse electrode. Go back to 7.0 solution to make sure you are still properly calibrated. Rinse electrode when finished. Do NOT reuse the calibrating solutions. Use only enough to cover the electrode. This should be done daily.

Q:  What does TDS mean?

A: TDS means Total Dissolved Solids (Conductivity). This is the calibrating solution used to calibrate the Conductivity Meter. Set the pH/Conductivity Meter to the TDS/Conductivity mode. Insert electrode into the TDS solution. Calibrate the meter to the TDS solution setting. When finished, rinse electrode in distilled water. Do NOT reuse the calibrating solution. Use only enough to cover the electrode. This should be done daily.

Q: We found some old instruments purchased by my sister after she attended your courses years ago. The Conductivity/Salts meter is one made by PRESTO-TEK CORPORATION with address at 4101 Figueroa Street, LA Ca. 90065 (213)221-1178.

A: This is the preferred meter. It is no longer produced, so you are lucky you have one of these.

Q: I tried it today and got a reading of 6 on the lower scale. Is this correct?

A: No matter what pH or Conductivity meter you have, it must be properly calculated daily. The instructions and calibrating solution for this should be with the meter. Calibrating solution is still available if you need it.

Q: Could you help me. Is the computation to get the salts reading the same as the instructions in the manual which is x 4 divided by 100? But using the manual's formula does not seem to be quite right.

A: There is no computation necessary for that old meter. The top scale on the meter is the Salts Reading.

Q: I also found an old pH meter. The brand is MARKSON. The process is quite the same as the new one. The old instruments are a back up to the "high-tech" quality of the new one but learning how to compute the Salts with this meter can serve as a back-up instrument, just in case.....

A: On the contrary. The separate Salts Meter and the pH Meter with the flat probe are the preferred instruments. They are much more exact than the combination pH/Conductivity Meter that is recommended in the BIA Keys. A separate Salts Meter (different than the old one you have) is still available. A separate digital pH Meter with flat probe is also still available and highly recommended. Be sure to calibrate both meters daily. The pH probe has a limited life.

Anyone serious about learning this work should invest in a separate Salts meter and digital pH meter with flat probe immediately. The test is easier to accomplish and the results are more accurate.

Q: How do I calibrate the Markson digital pH meter?

A: The procedure is quite simple. Here it is:
1. Adjust meter to temperature of specimen (usually between 20-25 Centigrade).
2. Place probe in 7.0 calibrating solution.
3. Use Calibration knob to adjust to 7.0.
4. Remove probe and clean.
5. Insert probe in 4.0 calibrating solution.
6. Use the screw on probe attachment side to adjust to 4.0.
7. Remove probe and clean.
8. Re-insert probe in 7.0 to check adjustment. Adjust if necessary.
9. If still inconsistent, you have a bad battery or bad probe.

Q: How do I calibrate the old Presto-Tek conductivity meter? The one that does not require diluting of specimens for the higher than 30 readings.

1. Remove cover.
2. Pour in calibrating solution.
3. Press both switches.
4. Use upper left adjustment to adjust to mid-point (battery adjustment).
5. Use lower right adjustment to adjust to mid-point (calibration adjustment).