Bluelab pH 4.0 Calibration Solution — 250ml

Bluelab pH 4.0 Calibration Solution — 250ml

The pH 4.0 calibration buffer solution for all Bluelab pH meters — one of the two solutions you need to keep your pH readings accurate. Without regular calibration, pH pens drift over time and give readings that aren't what they claim to be; with calibration, Bluelab accuracy is maintained for years.

Why growers need calibration solution:

• Calibrates Bluelab pH meters to the 4.0 reference point — half of the two-point calibration (with pH 7.0 solution)
• Essential for accuracy — uncalibrated pH pens drift; a reading of 6.0 might actually be 5.5 or 6.5
• Calibrate every 2-4 weeks — standard practice for any serious hydroponic grower
• 250ml bottle — enough for many months of regular calibration
• Works with all Bluelab pH meters — Combo, Guardian, Multimedia, pH Pen

Who it's not for:

You need pH 7.0 solution too for two-point calibration — buy both, not just one. Don't reuse solution after it's touched the probe; pour small amounts into a separate cup, calibrate, then discard.

In stock now — ships same working day from our Staffordshire warehouse with free UK delivery over £100. Pick up in-store at our Stone shop (ST15 0SR) if you're local, or click & collect at checkout.