Swimming Pool pH & Total Alkalinity – Close Cousins!

June 8th, 2012 | Posted by Debbie in - How To | Pool Chemicals

chart of pH values

pH and alkalinity are extremely important measures of your swimming pool chemistry.

The pH level is probably the most important of the two but if the alkalinity is not balanced first, your pH will be hard to control. pH is a measure of how acidic your pool water is, and is measured on a scale of 0-14.  The ideal range for pH in pools and spas is 7.2-7.6.

If the pH and alkalinity are not balanced you can see many different things happening with your water.  Scaling, cloudy water and eye irritations are just a few of the problems you could be facing.

When the pH is too high, the water is less acidic and has a tendency to cause scaling or calcium deposits on the tile and in the filter system. These same minerals can also be the cause of cloudy water.  Effect of pH level on pool chlorine efficacy

pH can also affect how powerful the chlorine is in your pool. When pH is at 8.0, only 20% of your chlorine will be active available chlorine. 7.6 pH level, will yield 45% efficacy and at 7.2 – 66% of your chlorine will be effective.

Lower your pH back into range by adding an acid. Liquid muriatic acid can be used, or you can use granular Sodium Bisulfate, commonly sold in a package labeled pH down, pH minus or pH decreaser.

When the pH is too low, the water will become very acidic or corrosive.  When this happens, it tends to damage copper heat exchangers and other metal surfaces in the pool or pool equipment, and cause pits to occur in plaster pool surfaces and vinyl liners to weaken.

You can also experience eye irritation, itchy skin and brittle hair. In this case, you would add a bit of  pH increaser to raise the pH level. I recommend that you add increaser and decreaser in small amounts, wait a while and test the PH again. Then add more if necessary.

Another important fact to understand, is that anything that falls into your pool has a pH. A good example of this is rain water or leaves. Large groups of swimmers can drastically affect your pH level.

Alkalinity is a measure of the alkaline materials that are in the water. We need some alkalines in the water to serve as “buffers” for the pH. Total Alkalinity should be between 80-120 ppm (parts per million). It is always important to remember to adjust your alkalinity first and then the pH. Alkalinity and pH are close cousins and both are influenced by the other.

If alkalinity is too high, your pH could drift to an extremely high level very easily. If this happens, it can be difficult and slow to get it back down to normal. If the alkalinity is too high, you could see signs of scaling and very cloudy water. If this should happen, you can bring your alkalinity down with pH decreaser.  pH down is used to lower the alkalinity as well as the pH in your pool water.

If alkalinity is too low, it will be very hard to control the pH. You will probably find that the pH measurement is bouncing all over the place.  Low alkalinity can be very corrosive, eating away at pool surfaces as well as the pool equipment. If the alkalinity is too low, you will need to add Alkalinity Increaser. This is often referred to as Alkalinity Plus or Alkalinity Up. Once you have the alkalinity adjusted, you then adjust the pH.

If you find that you are having problems keeping your pH and Alkalinity balanced, there is a product that will help you tremendously. It is called Ahh-Some.  It has a funny name, but is a wonderful product that seems to lock pH and Alkalinity in place.

Taking care of your swimming pool is extremely important. You want to make sure your water is balanced so that your pool and the equipment are safe.  More than that, you want to be sure that the water your family is swimming in is safe. I hope this explains the relationship of alkalinity and pH, and why they are so important to test and balance on a regular basis.

Debbie Farnan
SPP Pool Enthusiasts

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