Basic Pool Chemistry

The Basics of Pool Chemistry
(and why they matter)

One cannot simply dig a hole in the ground, fill it with water, and call it a pool. Tempting as it may be. If you do this you would soon find your “pool” turning all sorts of fun colors and becoming home to all sorts of undesirable critters. In fact it would start to resemble a pond more than a pool in a fairly short amount of time. My aim for this blog is to help you avoid this fate by giving a basic overview of pool chemistry. We will be skipping how to “Open” or “Close” a pool for the season. People with backyard pools need to know how to do this but folks visiting public pools do not. If there is enough demand perhaps I will tackle the subject of Opening and Closing in another blog. Leave a comment on our facebook page and let me know.

There are Four basic measures that any public pool should be keeping track of. Probably the most well known is the sanitization element. Most commonly this is some form of Chlorine or Cl. This is the chemical that acts like an anti-bacterial. It keeps populations of unwanted microbes under control and keeps the pool water nice and crystal clear. Cl is not the only sanitization chemical out there. Bromine or Br is another one one and is more common in indoor pools. Other methods of sanitization have become more popular over the years including Salt Water pools and UV light methods. Unfortunately even these new fancy methods may still require the use of low levels of Cl or Br to also be used. For people who have sensitivity problems, I encourage you to try pools that use different sanitization methods and find the one that works best for you.

The second thing that all public pools need to keep careful track of is Ph. Or in other words they need to track how acidic or basic their pool water is. Perfectly neutral water is a 7.0. Cl and Br function best at 7.4, however, the acceptable range for public pools is generally 7.2 to 7.8. Readings slightly outside this range are not going to cause immediate trouble but should be corrected as soon as possible. Much of the time when people experience “red eyes” after swimming underwater with eyes open and no goggles, it is because the Ph is slightly off, not the Cl.

The final two reading that public pools need to keep track of are alkalinity and Calcium. Alkalinity is important because it is a Ph stabilizer. Without a proper amount of alkalinity the Ph can swing wildly and keeping it at a consistently comfortable can be very challenging. The ideal total alkalinity is a 100 but the acceptable range is about 80 – 120. Calcium is what determines the “hardness” of the water. Most people know this because of its affect on the taste of water. However, public pools need to make sure that the proper amount of calcium is in the water to prevent problems like water cloudiness or even damage to the pool equipment itself. 200 to 400ppm (parts per million) is the current industry standard for pools. It is unusual for pools to test this frequently as once the level of Calcium is established, it doesn’t change very much at all.

Well, I hope this review of pool chemistry has been informative and / or helpful to you. One final piece of advice. When traveling, I highly recommend bringing a few chemical test strips. Dip the strip in the water, wait the prescribed amount of time, then compare the color of the strip to the color scale on the container the strip came from. These strips are not super accurate, or even very close, but they should at least give you the confidence that there is Cl in the pool. CL (or Br) are what are responsible for controlling the “bad stuff”. So if the test is saying there is an acceptable level of Cl in the water then that is your best assurance that the water is both safe and well taken care of.

Swim Safe!

Mr Eric