Everyone put your thinking caps on because we’re going to go technical today! To many pool owners, the terms “break even chlorination” or “breakpoint chlorination” can sound intimidating and to be quite honest, I was intimidated at the start as well, until it was explained to me in an easy to understand way. We here at Mr Pool Man will now attempt to explain these terms as friendly as possible with a splash of science just to keep it interesting!
5 Minute Read
What is Break Even Chlorination or Breakpoint Chlorination
In the simplest terms, break even chlorination or breakpoint chlorination is the point in which your pool’s demand for disinfection and sanitasion has been met. This means that your pool is killing all of the bacteria and algae in it, and all of the undesirable elements in your pool has been oxidized. Think of this point as a glass being full and adding more chlorine will just be a waste.
Technical: Reaching break even chlorination or breakpoint chlorination is the level of free chlorine that is enough to oxidize the combined chlorine or chloramines. Chloramines are what gives the pool that “chlorine” smell. When people say there’s “too much” chlorine in the pool because of that smell, it is actually quite the opposite. There isn’t enough free chlorine in the pool to get rid of the chloramine, hence the smell.
How to Achieve break even chlorination or breakpoint chlorination
This is usually the point where pool experts will pull out the graphs and try to explain the science behind it all, which will eventually lead to eyes glazing over and people start to pull their hair out. We’ve decided to skip the graphs and just give the rule of thumb for residential pools, which we assume is what you have.
You’ll basically need to add TEN TIMES chlorine to the level of chloramines as tested to reach break even chlorination or breakpoint chlorination.
For example, if your tested CC ppm or chloramine level is at 0.7 ppm, you would need to add enough unstabilised chlorine to reach 7.0 ppm. That’s it! Another example? If your CC is at 1.5 ppm, just add enough unstabilised chlorine to reach 15 ppm. Just multiply the tested number by 10 and that’s your target. We don’t need graphs to do that right?
Materials needed to achieve break even chlorination or breakpoint chlorination
You’ll only need two things to achieve break even chlorination. One is a DPD test kit to determine the exact level of chloramines in your pool. The other thing you’ll need is unstabilised chlorine to raise your free chlorine levels to reach break even chlorination.
Why unstabilised and not stabilised chlorine?
Stabilised chlorine contains cyanuric acid which protects chlorine from being burned out by the sun. If you use stabilised chlorine to increase your chlorine levels to hit break even chlorination, you will be unnecessarily raising cyanuric acid levels as well, making your chlorine less effective. And another plus to using unstabilised chlorine is that it’s much cheaper than stabilised chlorine as well, so that’s a big plus.
How to reach break even chlorination
The first thing you need to do is balance your pool’s pH levels. That came out of nowhere right? Remember, you pool’s pH level affects the effectivity of chlorine. If you have a high pH level, your chlorine won’t be as effective. So before adding any chlorine to your pool, make sure that your pH level is at the 7.2 level and total alkalinity is around 80-100 ppm.
The next step is to compute how much chlorine is needed to reach the break even chlorination point. For regular bleach, which has an 8.25% chlorine concentration, you would need to add approximately 115ml to raise the chlorine levels of a 10,000 Liter pool by 1 ppm.
Let’s take the previous example and say that you have a chloramine level of 0.7 ppm. To reach break even chlorination you would need to raise the chlorine level of the pool to 7ppm.
To raise a 10,000 liter pool’s chlorine to 7 ppm, we would need to multiply 7 by 115ml. So to hit break even chlorination, you would need to add 805ml to hit that mark.
Here’s a quick chart of the different types of unstabilized chlorine you can use and how much to add to raise a 10,000 liters of water by 1ppm
8.25% Bleach – 115ml
Trichlor – 12ml
Dichlor – 18ml
Cal-Hypo – 21ml
Armed with those numbers, you should be able to determine how much chemical you would need to add to reach break even chlorination without breaking a sweat.
Now that you know how much chlorine to add, dissolve the chlorine in a bucket of pool water and broadcast all over your pool and allow the pool water to circulate overnight. If you’ve done it properly, your CC or chloramine levels should be zero the next day and you’ve achieved break even chlorination. Don’t worry about putting too much chlorine, in cases like this, it’s better to put too much than put too little. The excess chlorine will be burned off by the sun in no time but if you put in too little, you won’t reach break even chlorination and you will have to repeat the process in order to reach it.
After reaching break even chlorination, don't forget to adjust the pH back to around 7.4 to 7.6.
Reaching Break Even Chlorination is something that has to be done periodically especially if your chloramine levels are high. This will ensure that your pool is perfectly safe to swim in and as an added bonus, you’ll get rid of the irritation and the “chlorine-smell” of your pool.
Read more about pool chemicals here in our Pool Chemistry 101 article.
Reaching break even chlorination is different from shocking your pool, read more on How to Shock your pool here.
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Happy swimming :)