Helpful or Harmful? What to Know About Pool Chemicals

Chlorine is the most common chemical added to pools is chlorine. It acts as a sanitizer, killing bacteria and algae. But is chlorine harmful?

It’s summertime, and in most of the country, it’s hot. That means pools of every shape and size are enjoying their moment in the spotlight (or sunlight, rather). If you are lucky enough to be a pool owner, then you know how satisfying going for a swim in the backyard can be. And you’re likely familiar with the need to test and treat the water to ensure it’s clean and inviting. But what exactly do those chemicals do to the water? What are they good for, and what do they harm? Are there any “go green” chemicals or alternative methods that may not be as harsh but are just as effective? Let’s learn what to know about pool chemicals by examining three of the most commonly used: chlorine (of course), muriatic acid and soda ash.

Note: This is not an exhaustive list of pool chemicals. Regardless of the intended purpose, you should always read the manufacturer’s instructions for use, cautions and warnings for each chemical you plan to handle.

1. Chlorine

How it’s helpful: It’s no surprise that the most common chemical added to pools is chlorine. The chlorine acts as a sanitizer — it’s very effective at killing bacteria and algae, which are the normal culprits that turn your water green. It does this by breaking down into different chemicals when it’s added to water. These chemicals, in turn, attack the microorganisms and bacteria in the pool, leaving your water clean and sparkly.

How it’s harmful: There are some harmful effects of using chlorine in pools. The most obvious is the smell. (Side note: That “chlorine smell” is typically an indicator that there is not enough chlorine in the pool.) It also burns your eyes and turns them red, and some people get irritated skin from it. In addition, it can fade your bathing suit colors and be hazardous to breathe.

The alternative: An alternative to chlorine is bromine. It works the same way but without the strong odor and skin and eye irritations. It is often used in hot tubs and indoor pools, though it isn’t as effective as chlorine on all types of algae. The big drawback (and the reason why it’s typical for indoor water areas) is that it doesn’t hold up to sunlight very well. Likewise, it’s much more costly than regular chlorine.

An eco-friendly (and better outdoor) alternative to adding chlorine is salt. This method employs the good effects of chlorine without the bad. A piece of equipment called a salt cell is added to the pump and filter system. The salt cell repeatedly breaks salt down into chlorine, and the result keeps free chlorine levels high and chloramine — what’s responsible for the potent smell and the eye and skin irritation — levels low. It’s important to note, though, that the salt cell unit does need to be cleaned periodically and replaced every three to five years.

2. Muriatic Acid

How it’s helpful: If your pool water’s pH level is too high, swimmers will have irritated eyes and itchy, sticky skin. The water will also become cloudy, and the chlorine will become much less effective. And if this condition is left untreated for an extended period of time, it can cause water scale, which can damage your pool equipment and possibly cause water leaks. The most common chemical added to lower pH? Muriatic acid.

How it’s harmful: Muriatic acid is a very strong acid. Not only does it give off strong fumes, but it will also burn your skin and ruin surfaces such as concrete, tile or stone. It’s imperative to wear protective clothing, including goggles, and to keep fresh water or a charged hose handy in case of spills, when dealing with muriatic acid.

The alternative: Sodium bisulfate, a dry acid, is milder than liquid muriatic acid. It doesn’t cause the same spikes in the alkalinity and pH levels in the pool that muriatic acid can cause. And it eliminates the problem of fumes in addition to being less likely to spill or splash.

Want an even better alternative? Luckily, manufacturers have joined the “green” movement and have been working hard to provide safer alternatives to muriatic acid, some of which are available for purchase now. In fact, it’s easy to find products that claim to be just as effective as the real thing without burning your skin and having up to 90 percent fewer fumes. Visit your local pool specialty store for more information.

3. Soda Ash

How it’s helpful: The lower the pH level, the more acidic the water is. The more acidic the water is, the more damage you’ll see on the pool’s surface (stains and corrosion, for example). Acidic pool water can also irritate your eyes, nasal passages and skin, and it causes the chlorine to evaporate quickly. That’s where soda ash, also known as sodium carbonate, comes into play.

How it’s harmful: Soda ash isn’t just harmful to your respiratory tract if it’s inhaled, other dangers of sodium carbonate also include skin irritation, eye damage and damage to your gastrointestinal system, if swallowed.

The alternative: An eco-friendly alternative is sodium bicarbonate, otherwise known as baking soda. Sounds like the perfect solution, right? Unfortunately, baking soda is only about half as effective at raising the pH. And it’s been known to raise the alkalinity of the water quite a bit. Therefore, you should only use sodium bicarbonate if the alkalinity is significantly low — so you don’t end up with two problems on your hand (low pH and high alkalinity) instead of one (low pH).

Want to learn more about the ins and outs of pool maintenance? Check out these five pool care mistakes you may be making.