JBL ProFlora CO2 Calibration Set - 3 x 50ml is the calibration kit for a pH electrode: calibration solutions at pH 7.0 and pH 4.0, 50ml of each, distilled water for rinsing, and three cuvettes to hold them. An electrode drifts with use, and a two-point calibration is how you bring it back to telling the truth.

Key Features

• Two-point calibration: pH 7.0 and pH 4.0, which is the pair that brackets the range a freshwater planted tank actually sits in.
• 50ml of each solution: enough for many calibrations, since each one uses a cuvette's worth.
• Distilled rinse water included: rinsing between solutions with tap water would carry its own pH into the next reading.
• Three cuvettes: one for each solution and one for the rinse, so nothing gets contaminated.
• For any pH electrode: the solutions are not specific to one meter.
• Calibrate on a schedule: monthly is a reasonable habit, and always before you trust a reading you are going to act on.

How To Calibrate

• Start in the pH 7.0 solution and let the reading settle before you set it. Electrodes take a moment.
• Rinse in the distilled water, dab the tip, then go into the pH 4.0 solution and set the second point.
• Pour out what you have used. Calibration solution that has had an electrode in it is no longer a reference.
• Rinse again before the electrode goes back into the tank or its storage solution.
• If the electrode will not hold a calibration or is slow to settle, it is worn out rather than dirty.

Good To Know

• A pH electrode must never dry out. Store it in its storage solution with the cap on, not in distilled water and not in air, because a dry glass bulb is usually a dead electrode.
• Electrodes are consumables. They drift as they age and eventually stop responding, so plan on replacing one every couple of years.
• Calibrate with fresh solution each time and never pour used calibration liquid back into the bottle.
• Rinse the electrode between solutions and dab it dry rather than wiping the bulb. The glass tip is thin.
• Keep the calibration liquids closed, cool, out of the sun and away from children.
• This kit calibrates an electrode. It does not include one.
• Check the dates on the solutions. Calibration liquid that has been open a long time is no longer the pH printed on the label.