Why Is My Pool pH Level Erratic?

Control the pH level to make swimming in your pool enjoyable.

You should check the pH level of your swimming pool at least once weekly. If you find that the level fluctuates widely up and down over a short period of time, your pool is experiencing what is called "pH bounce." This situation is caused by a problem with the total alkalinity, or TA, of the pool. Adjust it, and keep your pool's pH level, and the comfort of bathers, stable.

The Cause

The culprit behind the pH level bouncing up and down is the pool's TA being too low. The TA level is a measurement of the alkaline substances such as carbonates, bicarbonates and hydroxides that are in the water. You want to keep your pool's TA level between 80 and 120, because a proper TA level acts as a buffer to keep the pH level within the proper range.

Dangers

When the pH level bounces because of a low TA level, it poses dangers to both the pool and anyone who is in the water. Damage to the pool arises over time, when the chlorine used as a sanitizer becomes ineffective, opening swimmers up to the dangers posed by germs inside the water. The swimmers are in further peril due to the erratic pH levels causing burning to their eyes and noses, and irritation to the skin. The low TA level also damages the walls and floor of the pool, and corrodes metal parts of the pool facility.

Testing and Adjusting TA

Although the TA level should remain fairly constant if you regularly check and properly maintain the pool water, you should still check it on a regular schedule. Test the TA with a test kit that you can purchase from a local pool store and some general merchandise retailers, and follow the kit's directions to obtain a correct reading. To increase the level of TA, add sodium bicarbonate to the pool, which raises the TA and slightly increases the water's pH level at the same time.

Properly Adding Sodium Bicarbonate

Add sodium bicarbonate directly to the pool water. When you do, make sure the pool water is circulating, with the pump motor and filter on. Make sure that no one is in the pool at the time. Scatter the sodium bicarbonate around the surface of the water, starting at the deepest end of the pool, and work your way around the entire perimeter. Do not dump it into the pool.

References

• Pool Wizard: Total Alkalinity