What Chemical Turns Pool Water Blue? [Fact Checked!]


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In an effort to keep your pool looking as good as new, you might be tempted to try out a water treatment product. Perhaps you’ve seen the commercials where a handsome man in a swimsuit stops by to give a quick demo on how great a particular chemical compound is at dissolving stains from your pool walls?

If so, you’re in luck because we’ve got you covered on that front. Below, you’re going to discover a list of ingredients that are commonly found in swimming pool water treatments as well as their functions. Hopefully, this will help you decide whether or not to include these chemicals in your pool’s water. Keep reading.

Chlorine (Cl2)

Chlorine is an excellent disinfectant and odor destroyer. It’s also used to make pool water look beautiful by turning it a vivid blue. However, too much chlorine can actually do more harm than good. This is why it’s usually only found in swimming pools and spas. Some people are even allergic to chlorine. When used in large quantities, it can also cause serious health problems. Chlorine will combine with other chemicals, like bromine, to create compounds that are highly corrosive and harmful to your pool’s walls and equipment. In order to keep the integrity of your pool, it’s best to avoid using far too much of this chemical.

It’s also advisable to test pool water for chlorine before you use it for any purpose. This way, you’ll know how much concentration you’re dealing with and whether or not it’s safe for your pool. Chlorine can be determined by using a test kit that checks for the chemical’s presence in parts per million (ppm). For example, if your chlorine concentration is 0.2 ppm and you add another 0.2 ppm, your pool’s water will turn a beautiful shade of green. However, if it’s more than 2 ppm, then the water can become dangerously concentrated and start to stain the pool’s walls and furniture a bright blue. Once this happens, it’s usually too late because the damage is already done. This is why it’s always a good idea to test your pool water before using any chemicals to treat it. It’s also worth noting that over time, this can cause corrosion to metal objects in the pool, like your spa jets or water heater. Since these chemicals are highly concentrated, it’s best to avoid touching them with your hands and always use proper protection when handling them.

Bromine (Br2)

Bromine, like chlorine, is an excellent disinfectant and odor destroyer. It’s also what gives pool water that brilliant blue color many people are so enamored with. While it can be a great addition to your pool, it also has the potential to do a lot more damage than good. In order to keep the integrity of your pool, it’s best to avoid using too much bromine in any way. The same rules apply to testing for this chemical as for the chlorine. Also, just as with chlorine, too much bromine can cause serious health problems. These include nosebleeds, skin rashes, and even some respiratory issues. Since this chemical is so potent and can do so much damage, it’s always a good idea to be mindful of how much of it you use and for what purpose.

Hydrogen Peroxide (H2O2)

Just as with chlorine and bromine, too much hydrogen peroxide can do a lot of damage to your pool. This is especially true if it’s mixed with water since it becomes more powerful once it’s dissolved in liquid. It can also become highly corrosive, even in small quantities. For all these reasons, it’s best to avoid using hydrogen peroxide in your pool and always test it prior to use. It’s also advisable to dilute this chemical with water so it’s not as dangerous in larger quantities. Also, just as with the other two chemicals above, hydrogen peroxide can be corrosive to the pool’s metal fixtures and components, like your water heater and filters.

Ammonia (NH3)

Ammonia is a highly toxic chemical that is extremely corrosive. In fact, it’s so acidic that it can eat away the steel in your pool’s walls and equipment in just a matter of minutes. While it’s toxic in a variety of forms, it’s usually presented in a liquid form that people can easily handle. This makes it ideal for use in household cleaners and fertilizers as well as in pool water treatments. However, while it’s toxic in large quantities, it’s also highly flammable. This is why it’s always a good idea to handle ammonia with extreme caution and always wear proper protection when working with it. The general rules for using this chemical stay the same as above: avoid using too much of it, handle it with care, and always test it before use.

Sodium Hypochlorite (NaOCl)

Like the other two chemicals mentioned above, sodium hypochlorite can be used to make your pool water look good as new again. It also has the potential to do a lot of good for your pool. However, as with the other two compounds, too much sodium hypochlorite can do more harm than good. This chemical is highly concentrated and even in small quantities can be extremely corrosive. It’s also extremely flammable and can cause skin irritation in some people. While it’s highly effective at removing stains and toxins from your pool, it can also do a lot of damage. This makes it a risky chemical to use unless you fully understand what you’re doing and have all the proper safety equipment ready. One of the best things about sodium hypochlorite is that it’s relatively inexpensive and can be found at most chemical stores. This makes it an ideal compound for use in pool water treatment because it lowers the overall cost of ownership. Also, just as with the other two chemicals above, too much sodium hypochlorite can cause corrosion to your pool’s metal fixtures and components, like your water heater and filters.

Alcohol (CH3CH2OH)

Alcohol is a widely available chemical compound that is extremely toxic in large quantities. This means that even in small amounts, it can be harmful to your health. It’s also very flammable and can cause damage if it comes in contact with open flame or sparks. While it might be tempting to use this chemical to clean your pool, there are always better options out there. Instead of trying to scrub away your pool’s stains with a few swipes from an alcohol-based product, give the water a quick dip in a pool sanitizer. This way, you’ll maintain the health of your pool while also keeping its original glorious color. Don’t expect this chemical to do the same thing as above because while it will remove the stains, it will likely do so in a way that is not healthy for your pool. In fact, if you’re worried about the integrity of your pool, then it might be best to avoid using any alcohol-based products at all.

Acetic Acid (CH3COOH)

Acetic acid is another widely available chemical compound that is extremely acidic. This means that it can eat away at the concrete in your pool’s walls in just a short time. It’s also highly toxic in large quantities and even in minute amounts can cause damage to your health. While it can be great for washing away grime in your pool, it might not be the best choice for doing so. Instead of using a diluted form of this chemical, you might consider using a pool cue cleaner or noodle bowl cleaner to achieve the same result. These cleaners usually contain high levels of acid and can eat away at your pool’s concrete in no time flat. They are also easy to use and require little to no maintenance.

Isopropyl Alcohol (CH3CHOHCH2OH)

Isopropyl alcohol is a chemical compound that is widely available and used in many household disinfectants. It is also extremely flammable and highly toxic in large quantities. It is also what causes most pool water treatments to be poisonous if ingested. While it might be tempting to use this chemical to clean your pool, there are always safer and more effective options out there. Instead of trying to scrub away your pool’s stains with a few swipes from an isopropyl alcohol-based product, give the water a quick dip in a pool sanitizer. This way, you’ll maintain the health of your pool while also keeping its original glorious color.

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