MLA Citation: Bloomfield, Louis A. "Question 1047"
How Everything Works 17 Jan 2018. 17 Jan 2018 <>.
1047. What is pH and why is it so important to my garden pond and spa? — NW, California
pH is a measure of the concentration of dissolved hydrogen ions in water. When a hydrogen atom loses an electron and becomes a hydrogen ion—a proton—it can dissolve nicely in water. Actually, this proton sticks itself to the oxygen atom of a water molecule, producing a hydronium ion (H3O+) that is then carried around by shells of water molecules. The higher the concentration of hydrogen (or hydronium) ions in water, the lower the water's pH. More specifically, pH is negative the log (base 10) of the molar hydrogen ion concentration. That means that water with a pH of 6 has ten times as many hydrogen ions per liter as water with a pH of 7.

Pure water naturally contains some hydrogen ions, formed by water molecules that have spontaneously dissociated into hydrogen ions (H+) and hydroxide ions (OH-). Pure water has enough of these hydrogen ions in it to give it a pH of 7. But if you dissolve acidic materials in the water, materials that tend to produce hydrogen ions, the pH of the water will drop. If you dissolve basic materials in the water, materials that tend to bind with hydrogen ions and reduce their concentration, the pH of the water will rise. Water with too many or too few hydrogen ions tends to be chemically aggressive and we do best in water that has a pH near 7.

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