The Definitive Guide of Free Chlorine vs Total Chlorine

Chlorine And Your Pool.

What Is Chlorine?

free chlorine

Scientifically, Chlorine is a Halogen, simply meaning that it is salt form. However, you can buy chlorine in tablet or liquid form and can be purchased from your local hardware store or pool shop.

Chlorine is used in most swimming pools, either solely (chlorine pool) or in combination with salt (saltwater pool). It plays a major role in keeping the pool free of harmful bacteria, especially in pools, which have high traffic like your local swimming pool. Chlorine acts as a sanitizer disinfecting pools of naturally occurring bacteria and human-borne bacteria passed on from people with colds and flu etc. There are two main types of chlorine products beside the two forms (liquid and tablet); they are Total Chlorine and Free Chlorine. Don't worry I'll run through all the basics before I explain the different ways they both work.

I'll do my best to keep this simple; if you get stuck, you can always go to any of the blogs at the bottom of the page that offers more information.

Types Of Chlorine.

There is three types of chlorine, combined chlorine (CC), Free Chlorine (FC) also known as Free Available Chlorine (FAC) and Total Chlorine (TC). Many Pool owners get overwhelmed with the multiple types, but I will individually expand on each type and how they are used in layman's terms.

Combined Chlorine (CC): Chlorine in the water that is attached to dirt and organics.

Free Chlorine (FC) or Free Available Chlorine (FAC): Chlorine that is not attached and can be used to disinfect the water when needed.

*Total Chlorine (TC) = CC + FC.
*Note: If there is no Free Chlorine and lots of Total Chlorine your water is dirty, all the chlorine molecules have been attached to dirt, and it's time for a top up.

How Much Chlorine Do I Need?

This depends on a few factors; you can find this in the instruction manual provided by your pool manufacturer, instruction on chlorine box/bottle or by asking a pool maintenance worker at your local pool shop.

The deciding factors include:

The Surface Area And Volume Of Your Pool.

This makes sense, the bigger the pool, the more chlorine and the smaller pool, the smaller the concentration of chlorine. Otherwise, you would either get the irritated skin with too much chlorine, or it will be ineffective if the concentration is too small.

Pool Temperature
The Temperature Of Your Pool.

Chlorine dissolves at a more rapid rate when the temperature is higher. The safest option is to go into your local pool shop and chat to the staff just to be sure as the temperature can fluctuate if there is direct sunlight. There may be temperature-based instruction on the chlorine product box/bottle as well.

The Amount Of Sunlight On Your Pool.

Chlorine can easily evaporate when in contact with sun rays

How Many People Use The Pool.

To be safe, you will usually add more chlorine if a pool is busy to ensure effective sanitation. You will know how much to add by the chlorine test results. Just think about your local swimming pool would need to test the chlorine more often and throughout the day top up chlorine. Where as your household pool may only need to be tested once daily.

Free Chlorine Vs. Total Chlorine

So it's not which is the best, you need to understand the relationship between the two.

This will come after you:

  • Decide on a chlorine product.
  • Calculate how much you need to add.
  • Test your water regularly.

The best option for your pool is to ensure whichever chlorine product (tablet or liquid) contains enough free chlorine to attach to dirty compounds. Different Chlorine products contain different concentrations, which many may base their choice in chlorine product on, based on the deciding factors I mentioned above. However, there is another very important consideration, different chlorine products dissolve at different rates, which may be fine for smaller pools. The slower it dissolves the less evaporation and the more free chlorine available.

There is a Forum called Trouble Free Pool that answers a range of pool owner questions on chlorine and many other topics. Here is a link to the forum topic Free Chlorine vs. Total Chlorine.

I have included… If you need more information you can navigate to the websites and blogs which I have included links to. Or you can head over to your local pool store where a pool expert can tick all the boxes that you need to consider and send you in the right direction with the right product.

Now enjoy your pool and stay safe!

Other helpful blogs can be usually found on pool or pool part manufacturer websites.

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