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If your hot tub chlorine levels keep dropping, this detailed guide will explain the reasons and how to raise free chlorine in hot tub! Balancing the levels of bromine or chlorine is of the utmost importance for keeping the water clean in your hot tub.
Without the use of a decent sanitizer, your hot tub water will not be safe at all. You need the chlorine or other sanitizers to keep it completely safe and free from bacteria.
But what can you do if the chlorine levels continue to drop? More importantly, what’s the right level of chlorine that you should use in your hot tub?
There are several reasons why the levels of chlorine in your hot tub continue to decrease with the passage of time. In general, the levels of chlorine in your hot tub will decay naturally with the passage of time.
It’s completely normal and safe to replenish the amount of chlorine in your hot tub from time to time. If the chlorine levels are falling rapidly, you may want to check the pH levels of the water.
Similarly, you might want to shock the water in your spa as well and check to see if the water has been contaminated heavily or not.
Hot Tub Chlorine Levels Keep Dropping
Like most other substances, chlorine is used up every time it combats the contaminants and eats up the bacteria. More importantly, the excessive exposure to the ultraviolet rays from the sun is also a problem.
They are going to cause the chlorine levels in your hot tub to fall due to dissipation. It’s one of the reasons why you smell the chlorine when you are near the hot tub.
These are the reasons why you have to continue adding chlorine to the water in the tub. You can add a strong amount to your hot tub, going as high as 10 ppm.
This is going to make the chlorine so strong that it’s going to kill virtually all contaminants in the water, thus sanitizing it and making it safe for use.
After a few hours have elapsed, the chlorine will dissolve in the water, and its concentration will reduce to a considerably lower level, usually between 2 to 4 ppm. This is the ideal level for you to get in the pool as well.
There are a number of local strip tests that you can buy to check the levels of chlorine in your hot tub. With time, the level of chlorine is going to fall so low that you will have to replenish it again to keep the water clean.
Again, you must wait until the chlorine levels have dropped down a bit before you decide to jump in the hot tub. This is the cycle that you need to get familiar with.
It’s also one of the reasons why most people prefer using chlorine in their spas and shock the water every time they use it.
When the hot tub is not occupied, the increased concentration of chlorine can get to work and disinfect the water and eventually drop down to a safe level, thus making it suitable for you to jump in the hot tub the next time you want to.
According to the Centers of Disease Control and Prevention, the appropriate amounts of bromine or chlorine are the best sanitization options available and are crucial to maintain the overall germ levels of your water as well.
Once you establish a habit of replenishing the chlorine regularly, it’s not going to be a problem for you at all.
How Can You Check the Levels of Chlorine in Your Hot Tub?
The first thing that you need to do is invest in some decent test strips. There are quite a few available from Amazon, or you can always buy them from your local outdoor store.
It’s best to ensure that the test strips remain as dry as possible and to hold the strips from the corners only. This is going to prevent any residue moisture from your skin from contaminating the test strips.
Ideally, it takes around 45 minutes to an hour for the concentration of chlorine to drop to a safe amount. However, keep in mind that this figure usually varies, and in most cases, it could be a bit longer as well.
It is a wise idea to check the packaging and look for instructions to figure out the appropriate concentration of chlorine that you should add. If you don’t add enough chlorine, it’s going to create a bit of a risk: the water won’t be sanitized properly.
On the other hand, if you add too much, you might have to wait for a long while before you are allowed to jump into the hot tub.
Why Do I Constantly Have to Top up the Chlorine?
By now, you understand that topping up the chlorine levels in the hot tub is absolutely normal, and it’s something that you must do every now and then. But what do you think will happen when the levels begin to drop rapidly?
Or, what if the chlorine gets used up incredibly fast, thus preventing you from maintaining the 2 to 4 ppm which is ideal? There are several reasons why this might be happening. Let’s explore them one by one.
Inappropriate pH Levels
Without the right levels of total alkalinity or the right pH levels, it’s going to be impossible for you to maintain the levels of chlorine in the hot tub.
A number of hot tub issues usually arise from not checking the pH levels regularly. If you have a hot tub, you should make it a part of your daily routine to check the hot tub levels consistently.
Keep in mind that the chlorine levels are going to be heavily affected due to a pH imbalance. If the pH levels do not balance properly, the efficiency of your chlorine is going to be automatically affected.
Ultimately, to combat this problem, you will end up adding more chlorine than is required, and this could result in a much higher chlorine consumption (due to the lower efficiency) or not being able to maintain a safe minimum level.
The Rays of the Sun
The UV rays produced by the sun are also going to impact the chlorine levels in your hot tub. If the water is constantly exposed to the rays of the sun (the spa is kept under direct sunlight), it’s quite plausible that the levels of chlorine will dramatically decrease in a much shorter span of time.
Fortunately, this problem is quite easy to fix. You just need to consider putting up a sunshade or a gazebo above your hot tub to prevent the sunshine from affecting the water directly.
It’s also incredibly important that you place the cover of the tub bowl when you are not using the hot tub. It might be a wise idea to get rid of the cover right after you have shocked the hot tub so that the chemical vapor produced due to a reaction in the water is able to dissipate easily.
This could also prevent damage to the vinyl cover of your hot tub. Once a few minutes have passed, you can easily replace it.
Excessive Use
The primary reason why we use chlorine is to ensure that the water in the hot tub remains fresh and clean. Naturally, if you spend more time in the hot tub, it’s going to require much more chlorine usage as compared to if you use the hot tub sparingly.
If your chlorine levels start to rapidly fall, you might want to take a look at the extent of time you spend in the hot tub. If you have been staying in the hot tub for longer periods of time, it might require you to add more chlorine.
Keep in mind that the best routine to follow is to add the chlorine after you have just gotten out of the hot tub. This is going to ensure that the chlorine gets to work in killing the bacteria and then falling back down to safer levels, thus becoming ready for use again.
Contaminated Water
As you already know, the chlorine is going to be consumed much quicker if there are higher levels of contaminants in the water. Was there a drink spill or some food items thrown in the water of your hot tub?
Did you put on a bathing suit that had some washing powder residue? Anything that contaminates the water is going to make the chlorine work harder than it’s supposed to, and ultimately, the levels will drop faster than you will realize.
Ideally, you should remove all the moisturizer, dirt, soap, shampoo, and sweat from your clothes and your body before you decide to jump in the pool. Go for a wash in clean water before you decide to jump in the pool.
If you have more people coming in to join you in the hot tub, it would be a wise idea to ask them all to rinse a bit in clean water before they decide to jump in. It’s also a best practice to check the chlorine levels on a frequent basis in your hot tub.
How To Raise Free Chlorine In Hot Tub
If you find that your total chlorine is high but your free chlorine is low, then that’s a good indicator that your hot tub needs a shock treatment.
In such a case, you can add your weekly dose of oxidizer such as mineraluxe oxygen, beachcomber carefree or beachcomber ultra shock.
What these oxidizers do is to destroy chloramines and reduce wastage by burning it off and in the process raising your free chlorine levels.
Just after adding an oxidizer, it’s also important to run your jets for about 15 to 20 minutes with the hot tub lid open so that it can gas off.

Hello, my name is David Zal and I’m a plumber with more than 20 years of experience based in Englewood (Florida). I like to teach normal people how to make easy fixes in their homes. I believe that a lot can be achieved just with DYI and that’s why I started this blog.