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Free Chlorine Levels and How to Raise Them
Home Blog Free Chlorine Levels and How to Raise Them
30 Jun 2023  /  by Matteo Companion   /   0 Comments

Free Chlorine Levels and How to Raise Them

When dealing with chlorine levels in your pool, it’s important to ensure that free chlorine levels are above 1 ppm. If free chlorine levels are lower than 1 ppm, the person doing pool maintenance must take action to make the pool safe. 1 ppm or lower of free chlorine in a pool means the water does not have sanitizer, which allows for bacteria to multiply and algae to grow.


Although chlorine is effective when fighting bacteria and algae growth, what should you do if the levels don’t change after adding granules or tablets? How do you raise the levels of chlorine even if you’ve added chlorine?


If you have added chlorine to your pool and are still reading 1 ppm or below, the best plan is shocking your pool. This will often be effective, if you still receive low readings, it may be a high chlorine demand issue.


Keep reading step-by-step guides on what causes a low chlorine reading, and how to raise chlorine levels in your pool!

What Is Free Chlorine?

Free chlorine is the total amount of chlorine that is able to sanitize the pool’s water. This means that free chlorine is the chlorine that hasn’t been used for killing bacteria. If the pool has a low level of free chlorine, bacteria and organisms can build up over time. It is important to make sure that your pool has a free chlorine level between 1 and 3 ppm.

Free Chlorine: Free Chlorine is the amount of chlorine that is available to be used to kill off algae and remove contaminants from the pool.


Combined Chlorine (Chloramines): Combined Chlorine is the level of chlorine that has already been used to fight off contaminants in the pool sanitizing the water.


Causes of Low Free Chlorine Levels

There are many factors to consider when trying to determine what is causing the low free chlorine levels in your pool. Although there are many contributors to this issue, there are many ways to get your pool back on track and raise the free chlorine levels!

High Chlorine Demand: It’s important to check your pool when you have a large amount of swimmers in the pool. When debris is in the pool, it is good practice to use the necessary amount of chlorine to clean the pool. An increase of contaminants in a pool, makes the level of chlorine needed higher. The more contaminants in your pool, increases the demand for chlorine which can be hard to deal with.


High chlorine demand can take effect in pools for several reason. The most common times in which your pool may have a high chlorine demand is when it’s first opened. There are several reason for this, the first being a lack of treatment. This may also happen when there is a rain fall as there may be debris and runoff that may enter the pool.


You can determine if you have a high chlorine demand issue by throwing a package of shock into the pool. If the chlorine reading still comes back slow it is likely you have a high chlorine demand. To fix high this, it’s suggested you shock your pool 3x to raise chlorine levels so your pool can fix itself.


Heavy Pool Use


As previously stated when dealing with swimmers in the pool, it can significantly increase the need for chlorine. When swimmers are in a pool they can add sunscreen, dirt and oil from skin in the pool. This may cause the free chlorine to be lowered. It is good practice to shock your pool once a week or whenever there are significant amounts of swimmers. This will keep your free chlorine levels high and your water sanitized.


Sunlight and Low Cyanuric Acid Levels


Using a chlorine that is not stabilized( liquid chlorine or bleach) can cause levels to drop in sun. Stabilizer works as a form of protection for chlorine allowing the chlorine to last longer.


Checking stabilizer/cyanuric acid levels often can be quite helpful in regards to a few things. It helps to determine why there is such a high demand for chlorine. You can even test just to ensure that your chlorine is being used with maximum efficiency.


Very High Cyanuric Acid Levels


Having stabilizer/cyanuric acid in your pool is needed to make sure that chlorine in your pool lasts. However having too much of it can make the chlorine less effective making the pool require more. It’s important to check the CYA levels to make sure that your pool is not over the recommended amount. This will ensure that your chlorine is used to maximum efficiency. When dealing with stabilizer or cyanuric acid, the ideal level would be anywhere in the range of 30 and 50 ppm.


Most chlorinated tablets have stabilizer within them. Make sure to check the amount of stabilizer you’re adding to the pool to not go over recommended amounts.


Increased Organic Contaminants


As a result of rain storms, plenty of outside contaminants can make their way into your pool. Rain storms can affect the high demand of chlorine in many ways. The. first is leaves blowing from the wind into the pool. Another is organic contaminants being swept inside the pool from the rain water. After rain storms you should clean your pool of any visible debris. Shocking the pool will get rid of anything that entered from the storm.


Refilling The Pool With Fresh Water


If your pool is low on water due to backwashes, the water quality may be impacted when adding new water. The more water that is added to a pool will bring down the pool sanitizer. You can use stabilizer, or stabilized chlorine to return the pool to normal.


Not Adding Enough Chlorine


A reasons why a pool’s free chlorine levels may be low is because there may not be enough chlorine in the pool. If you have been adding chlorine tablets to the pool, check the pump to make sure it is constantly running. This should be checked often if the tablets are placed in the skimmer basket. It’s important to check your chlorine dispensers to make sure there are enough pucks to chlorinate your pool.


Not Enough Salt In Your Salt Water Pool


Salt water generators are a great way to sustain a good chlorine level in your pool. Although, without enough salt in your pool, the salt cell won’t be able to work effectively. This means the chlorine levels in your pool may be low.


Test the salinity levels every month to make sure there is enough salt to produce chlorine. Make sure to also check the salt cell often to know if it is running as it should be.


How To Raise Free Chlorine In A Pool


When opening a pool for the year there will be a build up in debris and a low/non-existent chlorine level. To deal with this, clean the debris from the pool and then later test the chlorine and add whatever amount is needed.


After a water test, make sure that your pH, alkalinity, and cyanuric acid are all within range. If you are struggling to keep your pH within range, refer to the following video to help with your pool.


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