Essentials PH Buffer 4 250ml
It is important to realise that unless you calibrate your pH meters with Essentials Buffer 4 and 7 at regular intervals the accuracy of the pH readings will be doubtful. Serious loss of crop performance may
Essentials buffers use two values of 4 and 7pH to calibrate your pH testers as they are at the outer reaches of the range of pH where you work in hydroponics i.e. 5.5-6.5. It is not necessary to calibrate pH testers to any other value for hydroponic use as we only work in a small area of the pH scale.