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Water Chemistry 101


Understanding chemicals and keeping them in balance

Chemicals:

Alkalinity: Adjusting the alkalinity to between 80 and 120 ppm makes balancing the pH much easier and prevents problems with the plaster, thus extending the life of your plaster. If the alkalinity is below 80 ppm add a small amount of pH buffer (sodium bicarbonate) daily until it reads above 80 ppm. If the alkalinity is above 120 ppm add one quart (4 ounces for spas) of hydrochloric or muriatic acid per day, with the equipment running, until the reading is below 120 ppm. Low alkalinity causes copper sulfate staining, premature breakdown of the plaster and can corrode equipment parts. High alkalinity causes calcium scale to form on pool surface which causes a stained and rough surface. Once the alkalinity has been brought into balance you should check and adjust it, if necessary, once a month.

pH: Keeping the pH in balance makes the chlorine more effective and cost efficient. Also, proper pH balance lowers eye and skin irritation significantly. It is recommended that you maintain your pH between 7.4 and 7.6. Note: the pH of the human eye is 7.5. To lower pH (most common), add hydrochloric or muriatic acid. To raise pH add soda ash. Sometimes it is necessary to add soda ash initially after adjusting alkalinity. Never add more than one quart of acid per day for a pool and 4 ounces per hour for a spa. Always add acid to the deep end of the pool with the equipment running. Once the pH has been balanced check the alkalinity again. You may need to add more pH buffer (sodium bicarbonate). Repeat the process until both alkalinity and pH have been brought into balance. Once the pH has been brought into balance you should check and adjust it once a week.

Chlorine: The purpose of chlorine is to keep your pool free of bacteria and algae. Maintaining the chlorine levels at 1.5 ppm to 3.0 ppm will help prevent algae and bacteria growth, this can be done by adding chlorine tabs to your floater, which will dissolve slowly, adding a small amount of chlorine every day. However, algae and bacteria can become immune to the normal maintenence chlorine and will occasionally grow inspite of the presence of chlorine, (especially in the warmer months or if the water is being heated.) So it becomes necessary to shock your pool occasionally with high levels of chlorine to kill the bacteria and algae. The best way to shock your pool is to add liquid chlorine. Depending on the size of your pool, add one or two gallons of liquid chlorine. Allways add liquid chlorine to the deep end of the pool. You can make the chlorine more effective by adding it at night as the sun burns off the chlorine very quickly.

Stabilizer: Stabilizer, also called conditioner or cyanuric acid, is used to make the chlorine more effective. Proper levels of stabilizer protect the chlorine from the uv rays of the sun. The recommended level is 30-50 parts per million. Low levels of stabilizer will cause excessive use of chlorine. High levels (above 150 ppm) of stabilizer will also cause excessive use of chlorine, will cause graying or pitting of plaster and is unsafe for swimmers. If your stabilizer level is low, add stabilizer. If your stabilizer level is high you can drain the pool partially and add fresh water. Anytime you drain your pool completely and refill, you must add stabilizer. Chlorine tabs come with stabilizer but this is only to maintain the level in your pool. Stabilizer should be checked monthly and adjusted if necessary.

Also check the calcium hardness and total desolved solids once a month. It is a good idea to take a sample of water to your local pool store once a month and have it checked.


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