Pool & Spa

Chlorine vs. Bleach

Chlorine vs. Bleach

Photo: poolassist.com.au

When it comes to maintaining a clean and clear pool, the two most common cleansers that many pool owners turn to are chlorine and bleach. But while many people use the two interchangeably, they are not entirely the same.

Chlorine and bleach will differ in chemical composition and hence their effectiveness in cleaning your pool. To help you decide which one suits your swimming pool best, here we look at some of the key differences between the two.

Overall Findings



  • Contains around 65% calcium hypochlorite
  • Other components are calcium & inert ingredients
  • Comes in solid states
  • Highly effective at cleaning pools
  • Often more expensive
  • Typically contains between 5% & 6% sodium hypochlorite
  • Other ingredients are water & salt
  • Comes in liquid form
  • Not as effective but still good enough
  • Generally more affordable

Chlorine vs. Bleach

1. Chemical Composition: Calcium Hypochlorite vs. Sodium Hypochlorite

The chemical composition is one of the key and perhaps most crucial difference between chlorine and bleach. Chlorine has calcium hypochlorite (Ca(OCl)) as the main active ingredient, but for bleach, sodium hypochlorite (NaOCl) is the active ingredient.

Pool chlorine will contain about 65% of the calcium hypochlorite, making it a more highly concentrated cleaning solution. With regular bleach, you get between 5 and 6% of the sodium hypochlorite. But, 6% seems to be the industry average.

Besides the calcium hypochlorite, the other components in pool chlorine are calcium and inert ingredients. Bleach, on the other hand, also contains water and salt. Salt is vital in bleach as it is what helps to keep the chlorine gas in its liquid state, but it is often in tiny amounts.

2. Form: Solid vs. Liquid

For chlorine, you can get it in either tablets, powder, or granules. The powder chlorine will often be added to the pool when you want to shock it, while tablets and granules maintain stable pool chlorine levels.

Because bleach comes in liquid form, there is nothing much that you need to do to control the chlorine levels in the pool when using it as you only need to pour it straight into the skimmer.

3. Effectiveness: Pool Chlorine is by Far More Effective

Given the higher calcium hypochlorite concentration of pool chlorine, it is often more effective at disinfecting your pool than bleach. When you add both calcium and sodium hypochlorite to the swimming pool, they will release hypochlorite ion.

If the pool’s pH is right, the hypochlorite ion transforms into hypochlorous acid (HOCl). The oxidizing properties of hypochlorous acid make it highly effective at killing germs, which means both products will be effective disinfectants.

However, chlorine is more effective at disinfecting pools as it contains more free available chlorine (FAC). FAC comprises hypochlorite ion and hypochlorous acid. If you were to dissolve a gram of pool chlorine into a litter of water, you would get a FAC level of 0.47 grams/liter.

However, if you dissolve the same amount of bleach in a liter of water, it will give you a FAC level of just 0.04 grams per liter. Hence, with chlorine, you get up to 11 times more FAC, making it the more potent disinfectant.

4. Conveniences: Both are Convenient in Different Ways

Chlorine offers you the convenience of not having to pour several bottles of liquid into the water, hence never dealing with messy splashes.

On the other hand, with bleach, you will get the convenience of never having to pre-mix it or pour it into the pool in a certain way.

5. Value for Money: Bleach Offers a More Affordable Cleaning Solution

Bleach is a more affordable product when compared to chlorine. A gallon of bleach can cost as little as $1 when you buy it in bulk and will hardly go beyond $3 per gallon even when buying one or just a few gallons.

For chlorine, you can expect to pay anything from $2.5 to $6.5 per pound. Sometimes the cost is even higher depending on the form and brand you are buying.

Because you typically need to use more bleach to get the same cleaning effect of chlorine, many people tend to assume that the prices even out at some point, which is not the case.

For example, you need about a gallon of bleach to get the same cleaning effect as 3/4-pound chlorine. Hence, if your pool requires 1.5-pounds of chlorine, you will need 2 gallons of bleach for the same effectiveness, which is still way more affordable than the chlorine.


The choice between chlorine and bleach will always be personal, as every pool owner seems to have specific preferences.

However, if you prefer a specially formulated product for cleaning your pool and is hence more effective, chlorine is the best choice for you.

On the other hand, bleach offers a more cost-effective solution for those looking for a cheaper way of maintaining their pool.

Clipped Head

  • D-shaped head
  • Requires a small magazine
  • Provides less holding power
  • Prone to overdriving
  • Can be paper collated
  • Hard to pull out
  • Affordable

Round Head

  • Round-head
  • Requires a large magazine
  • Gives more holding power
  • Hard to overdrive
  • Requires plastic or wire-weld collation
  • Easy to pull out
  • Expensive
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