What is Chlorine Demand in Swimming Pools?

Pool owners are no strangers to chlorine and its importance in sanitising pool water. Whether you prefer using chlorine tablets or granuels, ensuring that chlorine levels are as they should be is an essential part of keeping a pool safe for swimmers.

However, new pool owners may be less familiar with the term ‘chlorine demand’. Here, we take a look at what chlorine demand is and the effect it can have on your swimming pool.

 

What Is Chlorine Demand?

Essentially, chlorine demand is the inability for your pool water to maintain an adequate residual level of chlorine. No matter how much chlorine is added, your pool will ‘use up’ the treatment without actually sanitising the water.

If your pool is experiencing the effects of chlorine demand, when you test the water, it will show inadequate levels of chlorine despite how much you have added.

 

What Causes Chlorine Demand?

Understanding why you are experiencing chlorine demand is an important step towards resolving it.

Chlorine demand can occur for a number of reasons. It may be down to:

  • Poor pool management - if you don’t stay on top of shocks or regular water treatments, chlorine demand may come into effect.
  • Heavy use without equally intensive treatments – lots of bathers will introduce more contaminants that increase oxidation levels and tie-up free, available chlorine, causing a demand.
  • Heavy rainfall that interrupts chlorine levels – pollutants in rainwater can compound the issue.
  • Resistant algae – an abundance of organic matter can use up chlorine more rapidly.
  • Periods of disuse – water can become stagnant and the pool’s chemical balance will become compromised.

As you can see, chlorine demand will usually be caused by some kind of contamination. If your water is cloudy or green, you will need to check your chlorine levels. Find out how to use a chlorine test kit to ensure you can properly assess your water chemistry. 

A blue-tiled pool with railing

 

How Can Chlorine Demand Be Fixed?

Treating chlorine demand can seem like a daunting task when any chlorine you add does not seem to be sanitising the water as you expect, but it is not impossible to solve.

One way to counter chlorine demand is to add as much chlorine as possible. For this, you will need a fast-acting chlorination product such as a shock. Shocking your pool at night will ensure that the sun cannot burn away any chlorine.

As with any potential issues with your pool, preventing problems before they begin is always better than having to resolve a prospective issue that could be costly and time-consuming.

Ensuring that you are regularly checking and maintaining your water to help prevent the development of chlorine demand is crucial. You may also be interested in reading more about chlorine lock to better understand how chlorine can behave in your pool. 

 

Keeping your swimming pool chemistry in balance is an essential part of pool maintenance. If you are in need of swimming pool chemicals or treatments, remember we have everything you require right here at 1st Direct Pools!

For further guidance on caring for your pool, don’t hesitate to contact our knowledgeable team.