It’s the first test on the strip, people. And it’s important-very important.
“In chemistry, pH (Potential Hydrogen) is a measure of the acidity or basicity of an aqueous solution. Pure water is neutral, with a pH close to 7.0 at 25 °C (77 °F). Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline. “
High pH in swimming pool water can cause the following things to happen:
- calcium buildup on pool walls and floor- usually looks like white spots or flakes
- dull or cloudy pool water
- chlorine drop or lack of effectiveness
- red, burning eyes or nose
- dry and itchy skin (like this)
Lowering the pH of pool water
Adding an acid to the pool water reduces the pH. The most common chemicals used to reduce high pool water pH are:
- muriatic acid – (30% hydrochloric acid)
- sodium bisulfate – granule pH reducer, (dry acid, or ‘pH’ down)
Acid is normally added to water and mixed before treating the pool water. Make sure the pump is running on high speed while distributing the acid around the pool’s perimeter. If you have a chlorine generator, most likely you also have high pH. The chloride generated through the conversion of salt (NaCl- sodium chloride) into the ‘free chlorine’ has a dramatic impact on the pH levels in the pool.
Low pH in swimming pool water
Low pH in swimming pool water can cause the following things to happen:
- corrosion of any metal in contact with the pool water (especially the heater!!)
- staining due to metal corrosion (you will see this around the pool lights)
- ineffective chlorine, even at high levels
- burning of the eyes and nose
- dry and itchy skin
- faded swimming suits and pool toys
Raising the pH of pool water
Adding a base raises the pH of the pool water. Low pH can be a result of acid rain and often happens after periods of heavy precipitation. The normal tendency of pool water pH is to rise through exposure to wind, sunshine and bathers.
The most common cause of consistently low pH is low total alkalinity, which should always be adjusted with sodium bicarbonate before trying to increase the pH.
Of course, this is all very boring and complicated stuff…so if you’ve made it this far down the page, congratulations! You deserve a treat.