Testing & Adjusting pH Levels

pH LevelThe pH level is one of the most important factors in pool water balance and it should be tested and corrected at least once a week. The pH is the measure of the acidity or alkalinity the of the swimming pool water. A pH of 7.0 is neutral; below 7.0 is acidic and above 7.0 is alkaline. The pH of the pool should be kept within the range of 7.0-7.8.  The human body is slightly alkaline, with eye tears being at about 7.2 pH.  Thus, a more comfortable pH would be closer to 7.2 or 7.6.

If a pool is too acidic or the pH is low, metals begin to corrode, plaster finish wears off allowing algae growth, and sulphates are released causing brown and black stains.  The pool will require the use of more chlorine, because it will be released into the atmosphere, causing eyes and noses to burn and skin to get dry and itchy.

If the pH is to alkaline, or too high, calcium deposits begin to form, water becomes cloudy and murky, chlorine is less effective, filters clog up, eyes and nose burns, and skin gets dry and itchy.

It’s best to test the pH in the pool twice a week.  This can be done using pH test strips or test kits.  This will give an accurate reading of the current pH of the water.  Before you attempt to adjust the pH, it is vital to know how many gallons of water are being treated.  This will help you know how much chemical is needed to adjust the pH.  If you don’t know how many gallons of water your pool holds, you can take the volume of water (width x length x depth) and multiply that by 7.5 (there are 7.5 gallons per cubic foot).

Typically, most pools have a low pH.  Things like rain water, foreign objects in the pool, dirt and debris, and oils from swimmers bodies can cause the pH to fall.  If the pH is too low, add sodium carbonate.  This is commonly labeled as soda ash, but may be labeled something else, depending on the manufacturer.  Keep the pump running to circulate the water as you add the chemicals.  To raise the pH .2 or from 7.0 to 7.2, you’ll need to add approximately 3 ounces of sodium carbonate for every 5,000 gallons of water.

If the pH is too high, add muriatic acid or sodium bisulfate.  Due to the many different concentrations of muriatic acid, it’s essential to follow the manufacturer’s recommendations on how much to add to adjust the pH.

Let the pool’s pumps run for at least an hour and test again levels again.  You will likely need to make more small adjustments until the pH is just right.  Be careful not to splash or spill the chemicals.  These can be very dangerous if they get on the skin or are inhaled.

Once the pH has stabilized in the range of 7.2 and 7.6, you can begin to adjust the chlorine levels.  When the pH is at the right level, the chlorine will be the most effective.

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