Since the so-called water-chemistry stuff is by far the biggest concern of aspiring AFOs, that's all we're going to cover in Prep School. You'll probably find that the approach to the subject of chemistry in the book is simple enough for you, but there's a ton of information there – so let's get some of the fundamentals out of the way right now.

We have to start with pH. That's pronounced "pee aich," and it's always spelled with a little "p" even if it is used at the beginning of a sentence. A simple definition of pH is a number which represents the acid-versus-base balance of water. The numbers run from zero to fourteen, for some crazy reason. Low numbers, from zero to almost seven, are considered ACIDic. Seven on the money is NEUTRAL. From just over seven up to fourteen represents water which is progressively more BASE-ic. (That's basic.) Take a look at the table below, showing the entire pH scale from strong battery acid through weaker acids like orange juice through tap water values, on up to caustic stuff like lye (or a similar super-high pH chemical called caustic soda).

Most state health laws require the pH value of pools to lie between 7.0 and 8.0; in other words, just slightly basic. (In still other words, definitely not acid!) As an AFO, you'll bust your buns (that means work diligently) to keep your pool's water at a chosen pH value, probably pretty near pH 7.4. There's lots of reasons to hold other nearby pH values in certain pools, but let's wait for the course to find out why.

"How?" on the other hand, is a reasonable question. Water's pH is increased by adding an "alkalizer" (a high pH chemical) like soda ash or caustic soda or even common baking soda. The pH is decreased by adding any acids – although, as with alkalizers, only a few types of acids are commonly used in pools. Remember, all sanitizers and other chemicals, soils, body secretions, and so on, as well as rain and the make-up water, will have some effect on pH, either up in the basic direction or down in the acid direction. The result of all the influences on a particular pool's water is where the pH ends up – and that's the value which appears on your handy-dandy pool-water test kit.

Prep School Basics :: Chemistry Fundamentals