Basic Swimming Pool Chemical Types

Chemical Categories

In order to use pool chemicals well, you need to know what they are . . . and what they do. It may be easier than you think: despite the jillions of packages, labels and brands you see in various pool stores, there are six basic types of chemicals: sanitizers, algicides, oxidizers, pH control chemicals, stabilizers, and 'balance' chemicals.

Sanitizers make the pool safe for people to swim in: their job is to quickly kill all critters in the pool that are too small to see. This includes bacteria, viruses, fungi, and oocysts (amoeba 'eggs'). Not all microbiocides are sanitizers: some, like copper kill too slowly to qualify --- but all sanitizers are microbiocides.

Algicides kill algae -- or at least, they are supposed to. Algae are little plants that may float freely about your pool, turning it green and murky, as green algae does. Or, they may colonize some surface of your pool, turning it yellow or brown, as mustard algae does. Although algae is not usually dangerous, its presence makes the pool unattractive to people, and attractive to a variety of other creatures large and small. Colonizing algae, like mustard or black algae, often share their homes (biofilms) with a variety of disease causing bacteria.

Oxidizers don't kill, exactly. They chemically 'burn up' trash in the water. This trash includes sweat, body and suntan oils, skin cells, urine, wind-blown debris, and so forth. And, just as burning garbage produces smoke and leaves ash, so chemical oxidation produces waste products. Some of these products are harmless -- such as nitrogen or carbon dioxide gases -- while others are quite irritating -- such as some forms of the so-called 'combined chlorine' or 'chloramines'.

Also, just as the way you burn leaves determines how much smoke and ash is produced, so the way in which you use your oxidizers can have a large effect on how obnoxious the byproducts are.

pH Control products allow you to manage your pH. What's pH? Just a number that indicates how acid or alkaline your water is. Zero (0) is generally as 'acid' as you can get: undiluted muriatic acid has a pH close to zero. Fourteen (14) is generally as alkaline as you can get: dissolved crystal drain cleaners have a pH close to 14. Pure water usually has a pH around 7. Lemon juice is acid: dissolved baking soda is alkaline. (Properly speaking, dry materials don't have a pH.)

Balance chemicals help you to avoid damage to your pool, either in the form of corrosion or scale deposits. Actually, it's a bit more specific than that: balance chemicals allow you avoid problems that result from having too much or too little limestone in the water (calcium carbonate). It turns out that water can only dissolve a small amount of limestone -- but that it's VERY determined to dissolve just that much. On the other hand, sometimes water will have too MUCH limestone: in this case, the water is just as determined to get rid of the extra.

Water rids itself of excess limestone by leaving ugly scale in a variety of places around your pool, most often on the tile at the water line, and also inside the pool heater. And, in concrete or plastered pools, water grabs more limestone by eating away at your pools surface: the marble 'sand' that is used in plaster is just another form of limestone.

Stabilizers help keep other useful chemicals around. Most swimming oxidizers, including chlorine, bromine, and hydrogen peroxide, are destroyed fairly quickly by sunlight, which prevents them from doing anything useful. Cyanuric acid (present in the trichlor and dichlor forms of chlorine, but also sold separately) is very effective at protecting chlorine. The Albemarle Company claims to have a stabilizer for bromine, but it has not been made widely available. I have heard that ICI or Zeneca, or whoever owns the Baquacil brand at the moment has worked on some boron/borax based compounds that may stabilize hydrogen peroxide, but I haven't confirmed this.

And finally, specialty chemicals are chemicals that do something else. There are a wide variety of types, with many functions. Some work, some don't. Professionals use them only rarely. Why? Specialty chemicals aren't usually needed if you take care of the basics.

Methods - Standard . . . or Easy

So far so good. Everything above is pretty much standard, and if anyone disagrees with anything here, I'm not aware of it. However, once you get into the specifics of pool chemistry, there is a LOT of disagreement.

The standard methods of pool treatment come from the manufacturers, were promoted by the NSPI (National Spa and Pool Institute - now replaced by the APSP), and most dealers. These are the methods you'll read about almost everywhere (except here). So, if you want to treat your pool like almost everyone else is trying to treat theirs, read no further. Go directly to the standard pool chemistry page!

Then there are the simple pool methods. They aren't promoted by anyone, except maybe me. These methods are used mainly by some large pool service companies in California, Arizona and Texas, a few small pool service companies like mine, and a few homeowners and pool managers who have stumbled on them. Jock Hamilton, at United Chemical Co. used to promote high pH pool chemistry, but you won't find it on his website. Until two years ago, I didn't know anyone else used these methods. And, if you can read about these methods anywhere but here I would be surprised!

What is the difference?

Unfortunately, the chemistry that's involved in understanding the differences isn't simple. I'm working on simple explanations. Telling you what to do is simple; telling you why, isn't even close to simple. But I'm still going to try, eventually.

Meanwhile, it's not hard to understand that people who make more money if you use more chemicals won't work very hard to figure out how you can use less! Just as cardiac surgeons often don't study or promote Dr. Ornish's diet and program -- which may work as well as bypass surgery -- so pool dealers and chemical manufacturers don't study or promote methods of reducing your chemical consumption unless it involves buying something else from them. Quite honestly, I don't think most of them are trying to rip you off. But studying how you can use less without buying something more is just not what they are paid to do.

And, to put it plainly, the reason I discovered these methods, is that I made more money by doing so. My commercial pool service contracts are all flat fee: the less chemicals it takes to service one of my customer's pools, the more money I make. Ten years ago, I could do a better job with only 70% of the chemicals my customer's previously used. Last year, the average was down to 30%!

So it comes down to this: everyone who makes more money if you use more chemicals, promotes standard pool chemistry. Most, but not all, of the service companies who include chemicals in their contract, and who make less, if you use MORE chemicals use at least some of the methods we suggest.

Oh. And truth in advertising compels me to admit: I do hope to sell you something. Information. You don't have to buy any from me. I'm giving away a lot. But the easiest way to do pool chemistry is if some one will give you a recipe. Following a recipe is easy: designing one may not be. Designing a pool recipe depends on a bunch of things, including climate, season, filter type, bather load, tap water makeup, your preferences, and so on. But once you've got the recipe, you're fixed, at least till something changes.

And, I guarantee you'll like my recipe. If you don't like your pool you don't even have to give it back! Almost all you have to do is tell me you want your money back. Why almost, not all? You'll also have to send a brief email, telling me why you didn't like it. That's it.

So now you've got a choice.

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