General Hydroponics pH 4.01 Calibration Solution – QT
General Hydroponics pH 4.01 Calibration Solution – 1Q
GH pH 4.01 Calibration Solution Quart
General Hydroponics™ uses the highest-quality reference solutions, allowing growers to calibrate many popular brands of PH, EC and TDS meters (NaCl scale or the 442 scale). General Hydroponics™ technicians check each batch to ensure that our solutions are precisely calibrated and yield reliable readings each time they are used.