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A pH (potential of Hydrogen) measurement reveals if a solution is acidic or alkaline (also base or basic). If the solution has an equal amount of acidic and alkaline molecules, the pH is considered neutral. Very soft water is commonly acidic, while very hard water is commonly alkaline, though unusual circumstances can result in exceptions. The pH scale is logarithmic and runs from 0.0 to 14.0 with 7.0 being neutral. Readings less than 7.0 indicate acidic solutions, while higher readings indicate alkaline or base solutions. Some extreme substances can score lower than 0 or greater than 14, but most fall within the scale.
All glass electrodes have a bulb which must be kept hydrated and a reference junction which must be kept wet to prevent excess leakage of the internal electrolyte solution from the reference junction.
Ideally, storage solution since it has the same chemical make-up of what is in the electrode itself, but if that is not available use buffer 4 or 7 solution. NEVER STORE IN PURE (DISTILLED) WATER!!! In the case of electrodes that are continuously immersed, storage is not an issue since they are constantly wet.
"I use both the pH checker and the waterproof TDS HI 98312. They are simple to use and provide the accurate results I need."
- Goff, WI
"We have chosen and use Hanna pHep4 meters to test our pools for about 10 years. They are very accurate, easy to calibrate and dependable. We particularly like the replaceable probes. We also have TDS meters for field use."
- Suzie, OK
Reprinted from American Laboratory News February 2004, this article goes over improvements of pH measurement such as the combination electrode, more versatile pH glass, high-performance electrode junctions, and application-specific electrodes.