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How to calibrate the pH probe

About pH probe calibration

In order for your pH probe to remain accurate, it must be calibrated on a regular basis. New pH probes must always be calibrated before being put to use.

Probe maintenance and care

In order for the ProfiLux to give you the most accurate probe readings, proper calibration must be performed. Here are some general tips to go by:

  • Calibrate NEW probes before being put to use; pH, redox, conductivity
  • If you are going to calibrate a probe that is already in-use, make sure to first clean it with warm water or 50/50 mix of water and white vinegar to remove build-up
  • In-between calibration steps (pH), rinse and wipe the probe to prevent any cross-contamination between fluids
  • ALWAYS make sure the probe tip is kept clean and free from any detritus or foreign material
  • Make sure NO microbubbles get caught on the tip of the probe
  • Calibrate every 1 – 3 months
Probe calibration terminology

Before calibrating your probe, we recommend you become familiar with the terminology used during the calibration process.

Calibration tolerance
Used for telling the ProfiLux how much of a measurement swing is allowed during calibration. The larger the number, the large the tolerated swing, at the cost of probe accuracy.

By default, and in most cases, a calibration tolerance of 2 can be used.
A tolerance of 2 or 3 can be used for probes less than a year old. Probes greater than one year old, can use a tolerance of 4 or 5.

Calibration value 1
The value of the first calibration fluid that will be used

Calibration value 2
The value of the second calibration fluid that will be used

For example, if you calibrate a pH probe for saltwater, calibration value 1 would be 7.0 and calibration value 2 would be 9.0

What you’ll need…

In order to proceed with pH probe calibration, you will need the following fluids:

Required for saltwater aquariums
pH 7 calibration fluid (PL-0075)
pH 9 calibration fluid (PL-0076)
Required for freshwater aquariums
pH 4 calibration fluid (PL-0074)
pH 7 calibration fluid (PL-0075)
Listen for the 3 beeps!

During calibration, the ProfiLux will give the probe 900s (15 minutes) for the ADC values to stabilize. For steps 7 and 8, when you hear 3 beeps, the calibration step is complete. The amount of time it will take to hear these beeps will depend on probe age and set Calibration Tolerance.

pH probe calibration steps

  1. Press any of the arrow keys on the ProfiLux and select Sensor settings
  2. Select pH-value 1 or desired pH probe you want to calibrate
  3. Select Calibration
  4. Select (1) for Cali.tolerance if probe is brand new or less than one year old

5. Select the pH value of the first calibration fluid, pH 7.0 (SW) or pH 4.0 (FW)

6. Select the pH value of the second calibration fluid, pH 9.0 (SW) or pH 7.0 (FW)

7. Dip the probe in the first fluid and press the (√) key. When you hear 3 beeps, remove the probe from the fluid, wipe it clean to prevent cross-contamination of calibration fluids, then proceed to the next step.

8. Dip the probe in the second fluid and press the (√) key. When you hear 3 beeps, select YES to save calibration

9. Wipe the probe and put it back into the aquarium