Bluelab 4.0 Calibration Solutions, 18ml

pH 4.0 Calibration Solution, 18ml Sachets

A pH meter is only as accurate as its last calibration, and single-use sachets keep that calibration solution fresh and uncontaminated every time. Bluelab 4.0 Calibration Solution is a pH 4 calibration solution packaged in 18ml sachets, sold in a box of 30.

Sold as a box of 30 individual 18ml sachets.

Key Features & Benefits

• pH 4.0 calibration point — calibrates pH meters and controllers to the pH 4 reference point.
• 18ml single-use sachets — each sachet is sized for one calibration, keeping the solution fresh and uncontaminated.
• Box of 30 count — enough sachets for regular calibration across a full growing season.
• Compatible with standard pH meters — use with any pH meter or controller that calibrates against a pH 4 reference point.

Who Should Use Bluelab 4.0 Calibration Solution

This fits any grower running a pH meter or controller who needs a reliable pH 4 reference point for regular calibration.

About Bluelab 4.0 Calibration Solution

Bluelab 4.0 Calibration Solution is a pH 4 reference solution in single-use 18ml sachets, sold as a box of 30.

Frequently Asked Questions

Why do I need to calibrate my pH meter regularly?

pH probes drift over time and with use, so regular calibration against a known reference point like pH 4 keeps your readings accurate. Skipping calibration is one of the most common causes of inaccurate hydroponic pH readings.

What size are the sachets?

Each sachet holds 18ml of pH 4 calibration solution, sold in a box of 30. That's enough for regular calibration across a full growing season.

Why use single-use sachets instead of a bottle?

Single-use sachets keep each calibration solution fresh and free of contamination from repeated bottle use, so every calibration starts with a clean, accurate reference. That freshness matters because a contaminated calibration solution can throw off your meter instead of correcting it.

How do I use this with my pH meter?

pH 4 calibration solution works with any pH meter or controller that calibrates against a pH 4 reference point. Pair it with a pH 7 solution as well if your meter calibrates against multiple points.