Bluelab EC 2.77 calibration solution 250 ML

A 250 ml bottle of Bluelab reference solution at 2.77 mS/cm, for calibrating and testing EC probes.

Where your pH meter needs regular adjustment, a conductivity sensor is far more stable. You still need a reference, for two reasons: some meters calibrate against it, and the meters you cannot calibrate can still be checked with it.

Why Bluelab uses 2.77 rather than 1413

Most EC meters are calibrated at 1413 microsiemens per centimetre, that is EC 1.413. Bluelab chose 2.77 mS/cm, and the difference is not arbitrary.

A reading is most accurate close to the point you calibrated at. So the question is where you actually measure.

A grower sits around 1.2 to 1.8 EC in vegetative growth and around 2.0 to 2.6 in full flower. The centre of gravity of your readings is therefore higher than 1.4. Calibrating at 2.77 puts the reference at the top of your working range, so the part that matters falls between your reference and zero rather than outside it.

The practical consequence: use the reference your meter specifies. A Bluelab meter asks for 2.77, a Milwaukee usually for 1413. They are not interchangeable, because your meter expects to see one specific value.

Technical Specifications:

• Value: 2.77 mS/cm (2770 µS/cm)
• Volume: 250 ml
• Brand: Bluelab
• Use: calibrating and testing EC probes

Frequently asked questions

Can I use 1413 on a Bluelab meter?
No. Your meter expects to see a known value and corrects itself against it. The wrong reference sets it wrong instead.

My Bluelab meter cannot be calibrated at all.
That is true of the Truncheon among others. Testing still works, and that is exactly what this solution is for: if the value matches, your meter is still honest.

How often do I need this?
Far less often than pH buffer. Testing monthly is generous, and always after cleaning the sensor.

Can I pour used solution back?
No. Your probe always carries something over, contaminating the rest of the bottle.