GroStar pH 4/7/10 Calibration Kit

A Meter Is Only as Accurate as Its Last Calibration

Even a high-quality pH pen drifts over time — and a meter that hasn't been checked against a known reference can quietly feed you numbers that are off by enough to matter, especially during a sensitive growth stage.

This kit gives you everything needed to verify and recalibrate: one 8 oz bottle each of pH 4.0, pH 7.0, and pH 10.0 solutions — a full three-point set. Each is manufactured by Apera and certified to NIST reference standards within 0.01 pH at 25°C/77°F, so you can trust the baseline you're calibrating against.

The bottles are color-coded for quick identification and double-sealed to resist contamination between uses, with a 1-year shelf life when stored properly — making this kit something you can keep on hand and reach for routinely, not just when something seems off.

Key Features & Benefits

• Includes one 8 oz bottle each of pH 4.0, pH 7.0, and pH 10.0 calibration solutions — covers the reference points you need to verify and calibrate your pH meter accurately.
• NIST-certified to within 0.01 pH at 25°C/77°F — gives you a trustworthy baseline so your meter's readings reflect reality, not drift.
• Color-coded, double-sealed 8 oz bottles — make it easy to grab the right solution at a glance while keeping each one protected from contamination.
• 1-year shelf life — lets you keep the kit on hand for routine calibration without worrying about it going bad between uses.
• Made by Apera — brings a trusted instrumentation manufacturer's quality control to every bottle in the kit.
• Non-hazardous, room-temperature storage — keeps handling simple — just store the bottles cool, dark, and out of reach of children.

Who Should Use this calibration kit

This kit suits any GroStar pH pen owner who wants to verify accuracy before each measuring session — and especially growers who calibrate regularly enough that having reference solutions on hand saves a separate purchase every time.

How Often Should You Calibrate?

Most growers get reliable results by calibrating before each major measuring session — checking nutrient solution before a feeding, for example — and always after replacing a probe. Keeping a calibration kit on hand means you're never stuck guessing whether your last reading was accurate.

Frequently Asked Questions

What reference points does this kit include?

It includes one 8 oz bottle each of pH 4.0, pH 7.0, and pH 10.0 calibration solutions — a three-point set that covers the full range most growers need to verify across acidic, neutral, and alkaline references.

How accurate are the calibration solutions?

Each solution is manufactured by Apera and certified to NIST reference standards within 0.01 pH at 25°C/77°F, giving your meter a dependable baseline to calibrate against.

How should I store the bottles?

Keep them at room temperature, out of direct light, and away from children — properly stored, they carry a 1-year shelf life.

Are the solutions hazardous to handle?

No — they're non-hazardous and safe for normal handling with routine care, though they should still be kept away from children.

Will this work with any GroStar pH pen?

Yes — this kit is formulated for use with GroStar pH meters generally, including the GS1, GS2, and GS4 combo pen, for routine verification and calibration.