Basic Pool Chemistry: pH, part I

Okay, so before we go on to some of the more advanced aspects of pool care, I'm going to introduce you to the basics of pool chemistry.

This first lesson will be involving what we call pH.

pH is basically a measurement of how acidic or base the water is. pH stands for the "power" of "hydrogen". In essence, it is the measurement of the ratio of hydrogen ions (H+) to hydroxyl ions (OH-). The higher the concentrations of hydrogen ions, the more acidic the water is. The higher the concentration of hydroxyl ions, the more base the water is.

The basic pH scale is ranged from 0 (zero) to 14 where 7 is "neutral". The closer to zero, the more acidic. The closer to 14, the more base. This scale is logarithmic, meaning that each number on the scale is a factor of 10. Therefore, each number is 10 greater than the previous number or 10 times lesser than the following number. For example, a pH of 6 is 10 times more acidic than a pH of 7. In other words, a pH of 6 has 10 times more hydrogen ions than does a pH of 7. This works the same going the other way on the scale as well.

To put things in a clearer perspective, stomach acid has a pH of about 1.4 where Milk of Magnesia has a pH of about 10 and baking soda (sodium bicarbonate) has a pH of about 8.3.

The acceptable range for pH in a swimming pool is anywhere between 7.2 and 7.8 with the ideal range being 7.4 to7.6. In areas with hard water, a pH of 7.2 to 7.4 might be more ideal to prevent scale from building up on the side and surface of the pool.

We'll talk about scale in a later blog.

 - J