Changes

Buffer solution will be required to calibrate a pH meter, and generally has to be purchased separately from the pH meter itself. In general, it is recommended that a pH meter have a 2 point calibration method, which requires 4.0 buffer solution and 7.0 buffer solution. Many buffer solutions for pH meter calibration can be found on [http://www.amazon.com/s/?ie=UTF8&keywords=ph+meter+calibration+solution&tag=googhydr-20&index=aps&hvadid=33870947755&hvpos=1t2&hvexid=&hvnetw=g&hvrand=2358411058820273529&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_9h5a0pkyc9_b Amazon] or other retailers. Note that these buffer solutions do have expiration dates, and using expired calibration solutions can throw off pH meter readings.