pH Buffer solution should be used regularly, typically every day the meter is used, to calibrate your pH meters. Pour the buffer solution into a clean separate container, and never return used or unused buffer solution back into the container. Always keep the bottle tightly capped and adhere to the expiration date which is printed on the label.
BU5004-P, Buffer Soln, pH 4.00, 500ml
Simply immersing the electrode in the cleaning solution for 15 to 20 minutes will dissolve any mineral deposits or other coatings.