Some electronic meters require a �two point� calibration. pH BUFFER 4 is important as the lower calibration point in the two point calibration process. pH BUFFER 7 is important as the upper calibration point in the two point� calibration of electronic meters. This will ensure that meters accurately reflect the true reading at the lower end of the range. The ideal pH range for a nutrient solution is typically between 5.8 and 6.5. A pH value above or below this range can increase the likelihood that some nutrients become unavailable to the plant. A pH value of 6.3 typically works well for most plants. Regularly calibrate your pH meter with both pH BUFFER 4 and pH BUFFER 7 calibration solutions to ensure that your meter is operating with precision and accuracy between pH 4 and 7.