Bluelab pH Buffer 4 500ml

Bluelab pH 4.0 500ml

pH meters must be calibrated regularly to maintain reading accuracy. The calibration process uses two reference solutions at known pH values: a pH 7.0 buffer establishes the meter's midpoint, and a pH 4.0 buffer sets the slope of the response curve. Both steps are required for a complete two-point calibration. Skipping either produces a meter that may appear to read correctly in the middle of the range while being significantly inaccurate at the extremes that matter most in hydroponic growing.

Bluelab calibration solutions are manufactured to NIST-certified traceable standards, meaning the stated pH value is verified against a reference standard rather than approximated. This ensures that calibration brings the meter to a genuine reference point rather than simply adjusting it to an unverified solution. Decant into a small cup before use, discard after use, and never return used solution to the bottle. Store sealed in a cool, dark location.

This is the pH 4.0 slope calibration solution, supplied in a 500ml bottle.