GroStar EC 2.77 Calibration Kit

Confirm Your EC Probe Is Reading True

An EC probe can look fine and still be reading off by a meaningful margin if it's picked up residue or simply drifted with age, and there's no way to catch that without checking it against a known reference. This GroStar kit supplies a 2.77 EC conductivity standard solution specifically for that check, letting a grower confirm — or correct — probe accuracy before it affects a nutrient mix.

The solution is non-hazardous and made in the USA, and it stores at room temperature out of direct light between calibration checks.

Key Features & Benefits

• 2.77 EC conductivity standard — gives a known reference value to check probe accuracy against.
• Confirms the probe is clean and accurate — flags a fouled or drifting probe before it skews a nutrient mix.
• Non-hazardous formula — safe to handle as part of a routine calibration check.
• Made in the USA — produced domestically as part of the GroStar accessory line.
• Room-temperature, light-protected storage — stays usable between checks without special storage requirements.

Who Should Use This Calibration Kit

Anyone running an EC or conductivity probe — GroStar's or otherwise — who wants to confirm accuracy before mixing a nutrient batch is the fit for this kit, especially growers running feed programs sensitive to small EC errors.

About GroStar

GroStar, a meter and accessory line from Apera Instruments, offers this EC calibration solution to support the accuracy of its EC and combo pens, including the GS3 and GS4.

Frequently Asked Questions

How do I use this calibration kit?

Dip the EC probe into the 2.77 EC standard solution and check whether the meter reads that value, using the pen's calibration function to correct it if the reading is off. Rinse the probe with clean water afterward before returning it to use.

When should I check my EC probe against this standard?

Check it before mixing an important nutrient batch, or on a regular schedule if the probe is used often, since conductivity sensors can drift gradually without any obvious sign until a mix comes out wrong. A probe that hasn't been checked recently is the more likely source of an unexpected EC reading than the nutrient solution itself.

Is this solution safe to handle?

Yes, it's formulated as non-hazardous, so normal handling precautions — avoiding contact with eyes and washing hands after use — are sufficient. No special protective equipment is needed for routine calibration checks.

How should I store this solution between uses?

Store it at room temperature out of direct light, and keep the bottle sealed when not in use to protect the reference value from evaporation or contamination. A cabinet or drawer away from a sunny window works well.

Does this work with EC probes other than GroStar's?

Yes, since it's a standard 2.77 EC conductivity reference, it works with any EC probe calibrated to that value, not only GroStar's own meters. Confirm your meter's calibration point matches 2.77 EC before relying on this solution.