Choosing the Right Chlorine

Deciding what kind of chlorine is right for you and your pool can seem complicated. There are four chemicals that are commonly called chlorine (the gas that kills microorganisms in pool water) that are available for pool care. And having a little information about each kind of chlorine will make choosing much easier.

Sodium Hypochlorite

Sodium Hypochlorite choosing the right chlorine

Sodium Hypochlorite is a liquid pool chlorine. It is the same chemical found in bleach. It is usually the least expensive option. And it is easy to use in the sense that you just pour it into your pool. But the downside is that it is highly corrosive, and spills can ruin clothing, burn your skin, and even damage your liner if it is not addressed immediately. It is also very basic (as opposed to acidic), which means it can throw off your PH balance. It is unstabilized, which means you need to add Cyanuric Acid, or else sunlight will cause it to quickly looses it’s strength. The added expense of having to add acid to balance your PH and stabilize the chlorine may offset it’s low price.

Calcium Hypochlorite

Calcium Hypochlorite Choosing the right Chlorine

Calcium Hypochlorite is generally available in granular form. It dissolves quickly in water, so it can be poured directly in your pool, like Sodium Hypochlorite. And since it is not liquid, it is much less likely to cause the damage the Sodium Hypochlorite can. It is less basic than Sodium Hypochlorite, so it is less likely to unbalance your PH. And the Calcium in it will boost your Calcium Hardness, and help stabilize your PH levels. So it has a lot of positives. But it is not stabilized, so you will have to add Cyanuric Acid to keep it from loosing strength. It is also very reactive. In fact, it can cause a fire or even an explosion if it is accidentally mixed with some other household chemicals.


Chlorine tablets Choosing the right Chlorine

Trichloro-S-Triazinetrione, or Trichlor, is most commonly available in tablet form. This is usually more expensive than Sodium Hypochlorite or Calcium Hypochlorite, but pound for pound, contains more chlorine. It doesn’t throw off your PH levels, and when it breaks down, it produces Cyanuric Acid. So it is self-stabilizing. It dissolves slowly, so you can’t just pour it in the pool. You need a chlorinator (either inline or floating) or you can drop the tablets in your skimmer.

Dichloro-S- Triazinetrione

Dichloro-S-Trizinetrione is chemically similar to Trichloro-S-Tiazinetrione. It usually costs more than the other options. It contains a high amount of chlorine, and produces it’s own Cyanuric Acid. So it is self-stabilizing. But it produces a lot of Cyanuric Acid. More about Cyanuric Acid later. It is available in granular or tablet form. It dissolves too quickly to be used in a chlorinator. You have to dissolve it in water, and then add it to the pool. Like Calcium Hypochlorite, it is highly reactive, so you have to be very careful about not mixing it with any other chemicals.

Cyanuric Acid

Cyanuric Acid is a chemical that protects Chlorine from being broken-down by sunlight. If your pool is in direct sunlight and you don’t have enough Cyanuric Acid in your water, the Chlorine looses it’s strength very quickly. But if you have too much Cyanuric Acid in your water, the chlorine won’t work at all. It is safer to have too little of it in your pool than too much, because unlike the other pool-care chemicals, Cyanuric Acid doesn’t breakdown over time. Once it is in your water, you can’t get it out. If you have too much, the only remedy is to drain the pool and add fresh water.

What I Do With My Pool

I don’t like handling liquid chlorine. I’m a bit of a klutz and I have ruined too many pairs of pants and burned myself too many times to want to bother with it anymore. I have an in-line chlorinator in which I put four or five 3-inch Trichlor tablets once a week. That usually keeps the water clear. But sometimes I forget, and the water starts to get cloudy, or the bottom starts go get algae. Or sometimes I have an unusual amount of traffic in the pool (parties, etc.). And the water starts to look murky. Then I shock it with Calcium Hypochlorite (one of the small bags of granular shock), and vacuum the next day to pick up the dead algae. But your pool will be different from mine and will have unique needs. A year or two of trying different combinations will give you the experience necessary to keep your water clean and balanced. It takes a little time, and can be frustrating, but you’ll get there.


Girl in clear blue pool