What is pH?

Q: What is pH? Mine is frequently off, but my water looks fine.

A: Well, pH stands for “potential of hydrogen”, but I prefer to think of it as Potential Hazard. It is probably the single most important test in your pool kit, and keeping the pH in the correct range is one of the most valuable things you can do to keep your pool clean and safe.

pH is basically a measure of the relative acidity / alkalinity of a substance. It ranges from 0 (most acidic) to 14 (most alkaline), with 7 being neutral. Your blood, skin, saliva, and the diet Coke you drink all have pH values. When the pH in your body falls outside a certain range, it’s a sign that something is wrong. The same is true of your pool water.

The pH in your pool should generally be kept in the 7.2 to 7.8 range, although I shoot for between 7.4 and 7.6. If it gets outside this range, several things can happen.

The first is that your clients will be uncomfortable. Stinging, red eyes and itchy skin are symptoms of an undesirable pH. High pH levels also increase the likelihood of yeast infections – bad for dogs and people alike.

The second problem is sanitation. Chlorine and bromine do not work when the pH is too far out of balance. So you could be putting in chemicals to clean the water that are having little or no effect.

Finally, a pH that is too high can contribute to cloudiness in the water, while one that is too low can damage your pool and equipment.

A low pH can be raised with the addition of sodium bicarbonate – simple baking soda. Save yourself some money – instead of purchasing “pH Up” from the pool store, go to Costco and get a big bag of baking soda.

When the pH is too high, you must add acid to the water. Many people are reluctant to do this, believing that acid is a “bad” thing. Believe me, if your pH is too high, acid is a very good thing. It does require careful handling, though.

Changes in pH are easiest when they are small. Don’t wait until the pH is at the outside of the range to fix it. Once the pH is balanced and stable, testing two or three times a week (and making necessary adjustments) is probably all that will be needed. When you first set up the pool, after water changes, or after any major event (such as exceptionally heavy use or changing equipment), you should test and adjust daily until things stabilize.

If you are testing for multiple things (and you should be), and need to fix more than one, fix the pH first.

Final note: Many kits include a test for TA (Total Alkalinity). In general, having the TA in the right range will help stabilize the pH. However, changing one will change the other, and depending on other factors, it may be impossible to make both of them fall in the suggested range (this is not uncommon when using ozone, which tends to raise pH without a corresponding change in TA). When this happens, ignore the TA and focus on the pH. If your pH is in the right range and your water is not cloudy, TA is of little importance.

Answer courtesy of:

The ACWT Pool Guru:
Karen Hunter
22609 102nd Ave SE
Woodinville , WA 98077
425 487-3078