Hanna GroLine pH 4.01 Calibration Buffer — 500 mL

pH 4.01 is the acidic calibration point used to set the slope in a two-point calibration — essential for accurate readings in the 5.5–6.5 range most nutrient solutions run at. This 500 mL bottle of GroLine buffer suits growers who calibrate often.

Hanna calibration buffers are prepared to precise formulas and standardized against NIST-traceable reference standards, so your meter reads true every time you calibrate. Each container is airtight with a tamper-proof seal, and the lot number and expiration date are printed on the label. Unopened, Hanna buffers carry a 5-year shelf life.