Keep electronic aquarium pH measurement accurate with routine calibration. pH Calibration Fluid for Neptune Systems AquaController Apex pH Probes provides standardized reference points to ensure consistent and accurate test results. Calibrate pH probes on your Apex Kit or your Apex Jr Kit, customized with an optional Neptune Systems AquaController Apex pH Probe.

Choose the calibration solution based on the pH range your pH probe is expected to read.

Recommended Calibration Solutions

pH Probe Calibration
pH probes need to be calibrated to perform properly. The following procedure should be repeated periodically to keep your pH reading accurate as pH probes tend to drift out of calibration over time. As the pH probe ages, it will drift out of calibration very quickly or may not be capable of being calibrated at all. If this occurs, it will be necessary to replace the pH probe.

NOTE: If you wish to use the automatic temperature compensation feature, you should enable it before calibrating your pH probes. In this case, it is important for the calibration solution to be at the same temperature as the temperature probe at calibration time. The Apex system uses a 2-point calibration system, which results in very accurate readings between the 2 points and less accurate readings outside the points.

Choose the calibration solutions based on the range of pH the probe is expected to read. See the table below for recommended calibration solutions:

Recommended Calibration Solutions

NOTE: For best results, use pH calibration solutions in packets as the solution in bottles tend to shift pH after they have been opened.

To calibrate a pH probe:

1. Acquire the proper pH-calibration solution packets and place in aquarium water (unopened) to acclimate them to the system temperature.

2. From the Apex Display, open the pH calibration menu: Setup - pH Setup - pH Calibrate.

3. If you have more than one pH probe enabled on your system, use the up/down arrow keys to choose the probe you wish to calibrate, press Select or OK.

4. Use the up/down arrow keys to select the value of the Low Calibration Solution used, push Select.

5. Dry the Low Calibration Solution packet off and carefully open the corner of the low solution, just enough to get the pH probe inserted in the packet.

6. Remove the pH probe to be calibrated from the tank, rinse it in probe storage solution (or tap water), gently shake the excess solution off the probe, and place the probe in the Low Calibration Solution. Periodically swirl the probe in the solution to ensure an accurate reading. Ensure the probe is submerged in calibration solution at all times.

7. Wait for the low reading to stop changing. This may take a few minutes up to 5 minutes depending on the type and condition of pH probe being calibrated. The value of the reading while calibrating may not match the value of the solution being used, this is normal. Once the reading has stabilized, press Select or OK.

8. Use the up/down arrow keys to select the High Calibration Solution used, push Select.

9. Dry the High Calibration Solution packet off and carefully open the corner of the low solution, just enough to get the pH probe inserted in the packet.

10. Remove the pH probe from the Low Calibration Solution, rinse it in probe storage solution (or tap water), gently shake the excess solution off the probe, and place the probe in the High Calibration Solution. Periodically swirl the probe in the solution to ensure an accurate reading. Ensure the probe is submerged in calibration solution at all times.

11. Wait for the high reading to stop changing. This may take a few minutes up to 5 minutes depending on the type and condition of pH probe being calibrated. The value of the reading while calibrating may not match the value of the solution being used, this is normal. Once the reading has stabilized, press Select or OK.

12. The Apex system will use the calibration measurements to calibrate the pH probe.

13. The calibration fluid can be used to calibrate more than one probe; however, the pH calibration should be discarded after use, as they will degrade over time after opening.

If the calibration measurements were not accurate or were out of range, the calibration may fail, which will be indicated on the Apex Display. In this case, the default calibration settings will be used. You can attempt the calibration procedure again; however, this usually indicates that the pH probe is too far out of range and should be replaced.

pH Probe Maintenance
pH probes should be periodically cleaned and recalibrated for best performance. It is not recommended to clean the probes unless calibration is to be performed. The period between cleanings is up to the user but typically, every 1-3 months is normal. To clean the probe, gently brush the sides and tip of the probe with a soft brush to remove any debris. Rinse the probe in tap water. Soaking the probe in acid (vinegar) or alkali (borax) solution to remove mineral deposits is not typically needed but can be used to try and bring back an old probe that cannot be calibrated. Typical lifespan for a pH probe in aquarium use is 12-24 months.