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Free Chlorine Levels and How To Raise Them
Home Blog Free Chlorine Levels and How To Raise Them
25 Jul 2023  /  by Matteo Companion   /   0 Comments

Free Chlorine Levels and How to Raise Them

Dealing with chlorine levels in your pool is important to ensure that free chlorine remains above 1 ppm. If the free chlorine levels come back lower than 1 ppm then the person doing maintenance on the pool must act quick. 1 ppm or lower of free chlorine in a pool means the water isn’t safe. If the pool does not have any sanitizer, it allows for bacteria to multiply and for algae to grow.


Although chlorine works great against bacteria and algae, what should you do if the levels don’t change? What if they stay the same 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 receiving readings of 1 ppm or below, there are solutions. The best course of action would be to shock your pool with a chlorine shock. This will be effective most of the time, if you still receive low readings, it may be a high chlorine demand issue.


Keep reading for a guide on low chlorine level reading and how to raise the chlorine levels in your pool!

Free Chlorine: the amount of chlorine available to be used to kill algae and remove contaminants.


Combined Chlorine: level of chlorine that’s been used to fight off contaminants, sanitizing the water.


Causes of Low Free Chlorine Levels


There’s lots of things 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 to normal!


High Chlorine Demand: It’s important to check in on your pool when you have a large number of swimmers in the pool. It’s also good to check if there is lots of debris in the pool. Make sure to use the proper amount of chlorine to keep the pool clean and safe for the bathers. The more contaminants introduced into the pool can cause more chlorine to be required. The more contaminants you have in your pool at a given time increases demand for chlorine. This can be difficult to deal with as an owner of a pool.

High chlorine demand can take effect in a pool for several reasons. There are many reasons your pool may have a high chlorine demand. The most common is when you first open the pool up for the summer due to a lack of treatment. This also happens when there is a rainfall 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. In order to deal with a high chlorine demand, it is recommended you shock your pool 3 times. This will raise the chlorine up to high levels so that your pool can return back to normal.


Heavy Pool Use


As previously stated when dealing with a lot of swimmers in the pool, it can increase the need for chlorine. When swimmers are in a pool they can add sunscreen, dirt, and oil from skin in the pool. This increases the demand for chlorine in the pool. It is good practice to shock your pool once a week. Or whenever there are a lot of swimmers in the pool at one time. This will keep your free chlorine levels high and your water sanitized.


Sunlight and Low Cyanuric Acid Levels


When using chlorine that’s not stabilized like liquid or bleach, chlorine levels will drop in the sunlight. This is because stabilizer works as a form of protection for chlorine. This makes the chlorine last longer and act effectively. Checking your stabilizer levels often can be helpful when determining why there’s a high demand for chlorine. It also ensures that your chlorine is being used with maximum efficiency.


Very High Cyanuric Acid Levels


Although having stabilizer in your pool is needed in order to make sure that the chlorine lasts longer. Having too much of it can make the chlorine less effective meaning the pool will require more chlorine. Check the levels of CYA to make sure that your pool is not over the recommended amount. This will ensure that your chlorine has 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 so make sure you monitor how much you add. Do this to make sure you do not go over the recommended amount.


Increased Organic Contaminants


As a result of rain storms, plenty of outside contaminants can make their way into your pool. Rain storms contribute greatly to a high demand for chlorine. Whether it’s leaves blowing from wind, or organic contaminants, the demand for chlorine will rise. After rain storms, you should clean your pool of any visible debris. Make sure to also shock it to get rid of what got into the pool as a result of the storm.


Refilling The Pool With Fresh Water


If your pool is getting low on water due to backwashes or draining, the water quality may be impacted. This happens because of the introduction of new water that can offset the balance. The more water that is added to a pool also means the pool will be less sanitized. This will require more chlorine and shock to bring the pool back to the levels it was before.


Not Adding Enough Chlorine


One of the reasons why a pool’s free chlorine levels may be too low is a lack of chlorine being added. Check the pump to make sure it’s constantly running, especially if tablets are placed in the skimmer basket. It is also important to double-check your floating chlorine dispensers. Make sure there are enough pucks in the floater 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. However, without enough salt in your pool, the salt cell won’t be able to work effectively. This can make the chlorine levels in your pool decrease over time. Test the salinity levels of your pool every month so there is enough salt to sustain the chlorine levels. Make sure to also check the salt cell regularly to know if it is running properly.


How To Raise Free Chlorine In A Pool


When opening your pool for the season it is likely that there will be a lot of built up debris. There will also be low or non-existent level of chlorine due to its attempts to sanitize the pool. The first step to dealing with this is to clean the debris from the pool. Afterwards, test the chlorine and add whatever amount is needed. When you test your water you will also want to make sure that all levels are balanced. This includes your pH, alkalinity, and cyanuric acid. Struggling to keep your pH within range? Refer to the following video to help get you back on track!

There are plenty of types of chlorine and they all have different effects on the pool. By adjusting things such as pH or alkalinity you change the way the pool is balanced. Using a non-chlorine shock will decrease the level of combined chlorine. Non-chlorine shock however does not raise the free chlorine level in the pool. This is because the oxidation in non-chlorine shock breaks the combined chlorine without adding chlorine.


Shocking a Chlorine Pool: When shocking a chlorine pool it is best to use Pool Protect Fix Shock Treatment. Fix Shock Treatment will destroy all sorts of debris that is inside the pool as well as any sunscreen or body oils. By using this shock treatment, you will quickly eliminate any micro-particles by accelerating filtration. This shock treatment also lowers chlorine odours, is more gentle on the eyes and skin, requires little product. It will also not affect the pH level within the pool. It is recommended that a pool is shocked every week. However you can also shock your pool whenever you feel it is necessary.


Shocking a Salt Pool: When shocking a salt water pool it is best to use Pool Protect Salt Shock. Salt shock, similar to Fix Shock, can deal with all sorts of debris inside a pool. Salt Shock also increases the efficiency of sanitizer and produces softer water. It does nearly everything the Fix Shock does although the Salt Shock benefits salt water pools more. This is because it reduces the amount of wear that salt cell generators may face over time. This can make the system to survive longer.


What If The Shocking Doesn’t Work?


After shocking your pool you may realize that your chlorine levels haven’t changed. There are many reasons as to why the shock may not be working. The good news is that there are many solutions to solve these problems.


Pool Chemicals Out of Balance: After shocking your pool you may realize the chlorine levels haven’t changed. This can be caused by the chemicals in the pool being out of balance. Check to make sure that your pH and cyanuric acid levels are balanced. pH and CYA can make the chlorine levels fluctuate. To ensure this doesn’t happen, balance the pool before shocking it. By doing this you get maximum efficiency out of the shocking.


High Contaminant Load: If your pool has a high level of contaminants it may require stronger shock treatments. If your pool is dusty and clouds up when it is brushed, it may be mustard algae. If it is mustard algae further treatment will be required.


What If Your Free Chlorine Levels Are Always Low?


If you are getting low chlorine level readings, check the cyanuric acid levels of the pool. If your cyanuric acid level’s low, the chlorine level in your pool will be less effective in the sun. Not only will this decrease the efficiency, but it will also burn in the sun without cyanuric acid. Cyanuric acid can be the reason for a low chlorine reading. It can also be that your pool has a high chlorine demand. Debris in the pool caused by swimmers, or organic waste, may require more chlorine to deal with. This will ensure your pool is properly sanitized. This can happen when chlorine is being used faster than it is being distributed into the pool. As previously stated, shocking your pool can help fix this issue. If you consistently have low chlorine in a saltwater pool, you need to add pool salt or clean your salt cell.




Q: What should I do if my free chlorine remains too low?


A: If your chlorine levels are low, you should start by adding more chlorine to raise it. Use test strips shortly after to determine the level of free chlorine. You can then add chlorine granules to increase the free chlorine levels quickly. If that doesn’t work, you can shock your pool.


Q: How much shock should I use to raise my free chlorine?


A: The goal of shocking a pool is quickly raising the free chlorine levels. You want the free chlorine to be above your combined chlorine levels. So if you’re using Fix Shock, you should start by using one package and check your levels and see if more is necessary.


Q: Does shock that is chlorine free raise the free chlorine levels?


A: Non-chlorine shock will not have any effect on the chlorine levels of the pool. However, any non-chlorinated shocks will remove chloramines also known as combined chlorine.


Q: Is your free chlorine or total chlorine levels more important?


A: Both free chlorine and total chlorine levels are important. Your free chlorine levels should always be higher than your combined chlorine levels. If your free chlorine level becomes lower than your combined chlorine level, then you do not have enough chlorine available to sanitize your pool properly.


Q: Can you swim in a low chlorinated pool safely?


A: It can be hard determining whether a pool is safe to swim in or not. It is important to remember that if you had just filled the pool it will be ok to swim in. Although it may be safe to swim in immediately after the pool is filled, problems may arrive fast. Contaminants will build up fast which could cause illness or irritation. It is a much better idea to swim in a pool with chemicals. Before swimming make sure the pool is properly balanced along with adequate chlorine levels.

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