What Chemicals Do: pH

The information that follows is a continuation of our series on necessary pool chemistry that aquatics operators need to know. In the last post we covered chlorine; this time we will be covering the other half of the most important pair in pool chemistry. While this half isn’t in the same category as chlorine, which is a measurement and not a chemical itself, it is just as important. I’m talking, of course, about pH.

This is the next part of our series of posts designed to be shared with pool managers, head lifeguards, and other staff that will be assisting you in managing your pool chemistry.

What is pH?

The definition of pH, without getting too much into the complicated chemistry, is a measurement of how acidic, or how basic "alkaline" something is. The pH scale, registering from 0-14. Something with a pH of 7 or less is considered acidic, and anything with a pH of greater than 7 is considered basic or alkaline.

That’s all great information, but you may be asking yourself, “how does this apply to me and my pool?” Well, let’s talk about that!

Everything has a pH, and I mean everything; of course that includes all the things that get into your pool, such as people. More specifically, their shampoo and soap residue, their sweat, their spit, and yes, even their urine.

Many of the things that come into contact with your pool will have a similar pH rating to the water, but even minute differences in pH can have a measurable effect. But why is that? It is because the pH scale is logarithmic; which to put it plainly means that if you go from a pH of 7 to a pH of 9, that’s 100x more basic, not just 2 more basic.

Why adjust pH?

You may be asking yourself, what does it matter if your pH isn’t in the sweet spot of around 7.2-7.4, with the best being 7.3? Well, there are two answers for that question:

First, outside of that range, especially if it starts getting far beyond that, it can quickly become hazardous to your patrons; causing eye and skin irritation, or serious physical harm if it’s considerably outside of that range.

Second, your pool pH level has a direct effect on the effectiveness of the chlorine in your pool. Again, without going into too much complicated chemistry, the higher your pH the less effective your chlorine is at disinfecting your pool. So, if you have a pH of 8, whatever your chlorine level is will be less effective than the same amount of chlorine at a normal pH level.

What we use to adjust pH

There are two ways to adjust pH; the first is to make it more acidic, the second is to make it more basic. The two most common chemicals in the adjustment of pH are:

  • Muriatic Acid (Lowers pH) (liquid)

  • Soda Ash or sodium carbonate (Raises pH) (solid powder)

With both of these chemicals it is important to add/dissolve them into a water solution before adding them to the pool.

How Dangerous are the chemicals?

Muriatic acid is one of the most dangerous chemicals that are commonly worked with in a pool environment; obviously it is an acid, and can cause serious damage, particularly to the eyes, and lungs. So proper use of a respirator, eye protection, and gloves is absolutely necessary.

It is also highly recommended that when handling muriatic acid, you wear closed-toe shoes, and have as little exposed skin as possible, which means long sleeves and pants. Muriatic acid will not burn your skin off, or something as gruesome and dramatic as acid splashing portrayed in the movies, but it is important to thoroughly rinse any contacted body parts with fresh water. Also note that muriatic acid will quickly and dramatically stain any clothing it comes into contact with.

As for soda ash (sodium carbonate), it is relatively docile compared to muriatic acid; however it is advised to use the same respirator, eye protection, and gloves for sufficient protection. As with all chemicals, washing any skin that comes into contact with the chemical is important, even if it isn’t particularly hazardous.

pH in Daily Operations

You should monitor pH, as well as chlorine, periodically throughout the day, using titration kit, or a photometer. Ideally, your pH level should be between 7.2 and 7.4.

Further information on pH and other pool chemicals can be found here

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Have any questions about pH? Have any experience handling the chemicals involved? Let us know in the comments!

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