Growth Technology's pH Buffer 7.0 Calibration Fluid is used to calibrate pH meters, ensuring that readings stay as accurate as possible. pH Buffer solution — allows you to calibrate meters to pH 7.0 (neutral) Available in 300ml and 1 litre sizes Part of the Growth Technology range If your pH testing equipment isn't calibrated regularly, it can start to provide inaccurate readings. This can then cause you to administer nutrients that are either too alkaline or too acidic, certain nutrients get locked out, which inevitably leads to nutrient deficiencies.