My Pool Won’t Hold Chlorine and How To Fix It

Pool Care Chapters

If you own an above-ground pool, you understand the importance of monitoring the pH and chlorine levels in the pool.

In addition, you must maintain favorable conditions in the pool to contain bacteria and germs for pool users. 

Pool owners use chlorine to sanitize the pool but must monitor chlorine levels at least twice daily. These levels help you monitor the pool’s conditions, where the pool should maintain a sufficient amount of chlorine to maintain the pool’s balance and sanitization. 

Extreme variations or stagnation in the levels within a day could indicate problems with the chlorine levels or the presence of contaminants in the pool, spelling trouble. Read on to know why your pool doesn’t hold chlorine and how you can fix it. 

What Does It Mean for a Pool To Hold Chlorine?

If you add chlorine to your pool but still get zero free levels, the pool might be burning off chlorine quicker than the ideal rate. As a result, it doesn’t hold chlorine to balance the pool’s water composition. 

The color of your swimming pool also tells a lot about its chlorine levels. For example, the readings might be above zero but have hostile pool conditions like a green-colored or cloudy pool which you should look into to keep out bacteria and contaminants that inhibit the chlorine’s function.

The amount of free chlorine should tally with the total chlorine in the pool to help you maintain the proper pH levels. A slight dip or rise in the levels makes the swimming pool unfit.

Why Should Your Pool Hold Chlorine?

Your pool should hold chlorine to keep it free from bacteria and contaminants. A swimming pool with frequent and heavy users is more prone to poor chlorine levels or conditions and threatens its users. Pool owners should take a sample of the water for chlorine testing for monitoring and quick problem-solving.

In your pool, a high chlorine demand, where the free chlorine readings differ from the total chlorine levels, affects your chlorine readings. This condition indicates that your pool water is over-consuming the added chlorine or chemicals that regulate the water’s composition.

Reasons Why Your Pool Doesn’t Hold Chlorine

Your pool may not hold sufficient chlorine mounts for several reasons, primarily due to contaminants, stabilizers, or high pH levels. Here’s a breakdown of some reasons for worrying about chlorine levels in your pool. 

You Have Extreme or No Stabilizer Levels

Using a stabilizer in your pool helps protect pool water from the sun. The sun’s UV rays burn chlorine in the water quickly, causing an imbalance and high chlorine demand. Very little or no stabilizer in the water exposes the pool to high chlorine demand. 

High cyanuric acid levels in the water could consume the pool’s chlorine affecting its sanitization properties. Therefore, keep the stabilizer’s levels in check to avoid these preventable problems. 


Outdoor pools are prone to a high oxygen demand because they constantly get exposed to sunlight. Adding cyanuric acid acts– as the pool’s sunscreen and maintains the chlorine levels during the summer. 

Mind the amount of acid you use against your pool water volume to get the correct ratios. Keep tabs on its levels in the pool to avoid running out. Take care not to exceed the given ratio, as it may force you to partially drain the water to mitigate the high stabilizer effects. Consider doing it at night for maximum efficiency when shock-treating your outdoor pool. 

You Have an Algae Bloom

Still, pool water harbors different plants and organic materials like algae and leaves. Chlorine’s primary purpose is to sanitize and rid the pool water of bacteria or organic material. Algae consumes more chlorine when sanitizing the pool creating a high chlorine demand. 

An algae infestation pushes the demand and further deprives the water of sufficient sanitization. Even if you add in more chlorine to stabilize and sanitize the water, the high demand might outweigh the supply causing an imbalance and risk for bacteria and other contaminants. 


An algae bloom requires a high chlorine dosage for an extensive sanitization period. However, this mightn’t be enough if you can’t deal with the root problem- the algae. First, you must remove the algae from the walls and pool bed by brushing it off with the necessary tools and removing the debris and dirt from the process. 

Ensure you clean or replace the filters to avoid accumulating these organic materials and increasing the chlorine demand. Once you finish cleaning, shock the pool with ten times the chlorine concentration to kill everything in the water. 

This way, you foolproof your method, and you can start afresh. In addition, the process is more effective at night for outdoor pools to avoid losing higher amounts of chlorine to the sun’s rays. 

The Pool Has Other Contaminants

Besides organic contaminants, there are other pool contaminants like pee, poop, lotions, or deodorants from pool users, bacteria, bugs, animals’ waste, and rain or storms that chlorine needs to sanitize. These contaminants increase your chlorine demand to clear and sanity the pollutants. 


The solution to contaminants is to clear out the walls of the pools to remove the debris and pollutants and clean the filtration system. Don’t forget to shock the pool water before setting it back up for usage. 

Some experts recommend partially draining the pool and refilling it until you achieve clear water again. Check your contamination levels against your chances for success before committing to this process. 

You Have a Fungi or Bacteria Infestation

A fungi or bacteria infestation increases the chlorine demand in the pool. Therefore, you’ll need increased chlorine to counter the infestation and keep your waters safe and healthy for its users. 

Cleaning the water by scrubbing the walls and shocking the water with a high chlorine dosage improves the chlorine’s performance. 

High pH Levels

Although chlorine is slightly acidic, high pH levels render chlorine ineffective by limiting its sanitization effects in the water. At the same time, low pH levels allow the chlorine to dissipate more quickly, lowering its levels and demanding more chlorine in the water.

It would help if you worked on maintaining the pH levels to maximize its effects in the water. 

First, find out what affects your water’s pH levels. It could be rainwater, contaminants, or heavy pool usage.

Chlorine requires a pH level of between 7,2 to 7.8 to work effectively. Therefore, regularly check the water’s pH levels to maintain or adjust it for efficiency. 


Balance the pH using muriatic acid or baking soda for acidity and alkalinity. Test the water to check for changes after the adjustments for the best results. 

Insufficient Water Circulation Within the Pool

Inadequate circulation in your pool water has numerous downsides. First, you won’t get accurate results from parts of the pool. Each pool part will have different effects because of the uneven circulation. 

Since the chlorine in the water doesn’t get to all parts equally, some areas become under-sanitized while others are okay. It could be due to shorter or incomplete run cycles or clogged filtration systems hindering proper water circulation. 


Look at the run cycle setting and the filtration system. Extend the rn cycle daily to ensure it completes its process, enhancing water circulation. Check the filters in the filtration system if you need to replace or clean them to improve circulation and filtration. 

High Phosphates Levels

High phosphate levels often invite an algae bloom since they are algae food. In addition, it provides a comfortable environment for the algae to thrive, which depletes the chlorine in the water. However, science shows that if you maintain a certain free chlorine level, you can keep the algae at bay, thus maintaining your chlorine readings.


Aim at maintaining your free chlorine levels at three parts per million to keep the algae out of your pool water. Monitor the chlorine and phosphates level keenly and act accordingly once you notice any changes. 

A Faulty Saltwater Generator in Your Salty Water Pool

Salty water pools pose a different challenge from outdoor and other pools. First, it would help if you had a saltwater generator running efficiently to maintain your chlorine levels. Mostly, these generators have subtle indicators when they have a problem. 

Respond to these signages and work on a compensation plan to maintain your saltwater pool’s pH and chlorine levels. Also, look at the calcium or salt levels in the water to rule out any additional problems in the water. 

Leaving the Pool Unattended or Used for Long Periods

Leaving your pool unattended for long periods, like during the winter season, could promote the growth of algae and other contaminants. Therefore, it’s advisable to balance your pool before leaving it for long periods to improve its chances of maintaining the proper levels until opening. 

Fixing Your Chlorine Levels in Your Pool

These are the reasons that might affect the chlorine levels in your pool. Take note of the solutions and work towards eliminating preventable problems. Regular inspections and cleaning tasks help in doing your pool sanitization justice.

The Pool Care Handbook & Video Course

by Swim University
This is an illustrated e-book with detailed videos and step-by-step instructions on how to best care for your swimming pool. 
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