You’ll find a variety of chlorine compounds at your local pool, but not all of them are created equal. Knowing the differences between the various types of chlorine compounds can help you determine which one to use for your pool and how much of it to use.
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Chlorine
For decades, chlorine has been a mainstay in municipal swimming pools. It’s been used to keep the water in good condition, and it’s also been proven effective at killing bacteria and germs. While there are several grades of chlorine available, the most commonly used type is commonly referred to as “elemental chlorine” or simply “chlorine.” This is largely because elemental chlorine is the most effective at killing germs and is also the least expensive type of chlorine available. It also has a relatively short life span (less than a year) so it has to be frequently replaced. In most cases, chlorine levels in a pool rise as the water level drops, so it’s important to monitor and maintain a proper chlorine balance in your pool (more on that later).
Fluoride
Just like with chlorine, there is also an option for pools to use fluorides as an anti-algae additive. Just remember that when it comes to fluorides, more is not always better. Too much fluoride in the water can lead to health issues, particularly in children and animals. The proper concentration for fluoride is usually around 1.25 to 1.5 ppm, and it’s usually added to the pool at the beginning of the season.
Tetra-chloro-phosphate
Tetra-chloro-phosphate (or TCP for short) is considered a “winterizer” or “chilly water additive” for pools. It is most commonly used in combination with other chemical compounds in an attempt to keep the water in good condition all year long. TCP can also be used to “winterize” a pool by itself (in colder climates) or in combination with other chemicals in an attempt to keep the water clear (for those in warmer climates). While it can be used to “winterize” a pool, the general consensus among scientists is that it does nothing for the health benefits of the pool itself (i.e., the water is still perfectly safe to swim in). One of the main reasons for adding TCP to a pool is to help prevent algae from growing in the water. Algae can clog the pool’s filtration system, and it also gives the water a bad taste.
Alkaline
When it comes to pools, alkaline is the chemical compound of choice for most people. It is cheap, easy to use, and it has a long history of safe use behind it. The only downside is that alkaline water tends to become cloudy over time, so it needs to be constantly monitored and filtered if it’s going to stay clean and clear.
Hypochlorous Acid
Hypochlorous acid (HClO4 for short) is a chlorine compound that is more stable than common chlorine and can also be used in the pool’s water. The key difference is that hypochlorous acid is more stable than common chlorine because of its relatively high concentration of oxygen gas. This is also why it is most beneficial when used in conjunction with an ozone generator (see our article on the best pool cleaners for more information). While hypochlorous acid is more stable than common chlorine, it still breaks down and needs to be monitored and replaced frequently.
Chlorine Dioxide
Chlorine dioxide (ClO2) was originally developed as a safer, more eco-friendly replacement for chlorine. It is a very stable compound and it has an extremely long shelf life (up to five years if stored properly in a cool, dark place). Most swimming pool owners prefer to use chlorine dioxide because it smells pleasant and it also tastes better to people (no one likes bad tasting water, even though it’s perfectly safe to drink).
There are several advantages to using chlorine dioxide instead of chlorine, but one of the most important ones is that it doesn’t leave a residue behind. This is why most pool owners will tell you to add the chemical directly to the water instead of using tablets or gels to accomplish the same goal. Just keep in mind that too much chlorine dioxide can be harmful so always wear gloves when cleaning the pool with it. This way, you won’t accidentally ingest any while cleaning the water.
Activated Charcoal
Activated charcoal is another commonly used compound in pools that can be used to filter the water or as an anti-algae additive. It will neutralize harmful substances in the water and it also helps prevent them from being reabsorbed by the algae (which can cause serious health issues for both the pool and its users). Activated charcoal is most commonly used in conjunction with other chemicals in order to keep the water in good condition all year long.
Methane Thiosulfate
Methane thiosulfate (or MTS for short) is a chemical compound that is both effective and eco-friendly at stopping algae growth in swimming pools. It has been shown to reduce algae proliferation by 98% among other things. One of the reasons for its effectiveness is that it helps prevent algae from forming while it also deters it once it has formed. Simply put, it’s an algae killer that is also eco-friendly and affordable. Most people in the know prefer to use methane thiosulfate instead of traditional chemicals in order to keep their pools clean and crystal-clear.
Chlorine Trichloride
Chlorine trichloride (or CCl3 for short) is another compound that is used in combination with other chemicals in an attempt to keep the water in good condition. This compound, while not as common as the others mentioned so far, has been proven to be just as effective at preventing algae growth while also being completely harmless to humans and other aquatic life. Chlorine trichloride is a more environmentally-friendly option than many of the chemicals used in conjunction with it because it is non-toxic and it won’t harm the ecosystem like many others will.
All these chemicals and compounds are effective at killing algae and bacteria, but not all of them are created equal. Many people choose to add chlorine to their pool because it’s affordable and easy to use, but if you’re looking for an eco-friendly option that prevents algae and kills germs at the same time, you should try chlorine trichloride.