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A pH meter that hasn't been calibrated recently can drift silently off target, throwing off nutrient decisions before you notice anything's wrong. Bluelab pH 4.0 Calibration Solution solves this by giving your Bluelab pH Pen or meter a known reference point to calibrate against, keeping readings accurate and dependable.
Regular cleaning and calibration boost the longevity of your pH probes, and the pH 4.0 solution is a core part of that routine — a must-have in every grower's maintenance toolbox alongside Bluelab pH 7.0 Calibration Solution for standard 2-point calibration.
Available in 250ml (8.4fl.oz.) and 500ml single bottles, as well as box-of-6 case packs of each size — choose the option that matches your usage and restocking needs from the size selector.
A known 4.0 pH reference point keeps your meter reading true.
Regular calibration and cleaning with storage solution keep your pH probe performing longer.
250ml and 500ml bottles, plus box-of-6 case packs of each.
| Option | Volume |
|---|---|
| Single Bottle | 250ml / 8.4fl.oz. |
| Single Bottle | 500ml |
| Case Pack | Box of 6 — 250ml bottles |
| Case Pack | Box of 6 — 500ml bottles |
It's a known reference solution used to calibrate your pH meter or pen, ensuring readings stay accurate over time.
Yes. Standard 2-point calibration uses both pH 4.0 and pH 7.0 solutions together to ensure accuracy across your meter's full range.
It's available in 250ml and 500ml single bottles, as well as box-of-6 case packs of each size.
Regular calibration helps extend the life and accuracy of your probe — check your specific meter's manual for a recommended schedule.
The box-of-6 case packs are a good fit if you're managing multiple meters or calibrating regularly, while a single bottle suits occasional use.
Our specialists are happy to help. Call us or send a message and we'll get back to you within one business day (most of the time within a few hours.)
Equipping home growers, craft producers, and commercial operations across North America since 2016.
