Why Does the Chlorine in My Hot Tub Disappear?

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Why Does the Chlorine in My Hot Tub Disappear?

The general functioning of hot tubs is similar to the way swimming pools function. This is to say that they require chemicals for controlling bacteria and algae in them.

While bromine is the most preferred chemical, chlorine is largely used as the former is too expensive.The Maintenance of a correct level of chlorine in your hot tu b cannot be overemphasized.

 Low levels of chlorine in your hot tub make it non-sanitary, while high levels of the same make it unsafe for your skin.This is because your skin will dry out and get irritable.

Consequently, you want to check your chlorine levels in your hot tub regularly.  A weekly chlorine check is a good place to start, but the frequency can be increased with more frequent use.

But you might be asking, why does the chlorine in my hot tub disappear? Well, the contamination resulting from various causes is the main reason behind chlorine being used up in your hot tub as it battles the contamination to kill bacteria and keep the water clean.

As the most often used chemical in hot tubs to get rid of bacteria, chlorine performs a fairly simple chemical reaction.

When you pour chlorine in your hot tub, it breaks down into hypochlorite ion (OCl-) and hypochlorous acid (HOCl), among other different chemicals.  

These chemicals are largely responsible for killing microorganisms and bacteria by attacking the lipids that hold the cells together.

Consequently, the cell enzymes are rendered oxidized and harmless. However, HOCl and OCl- operate differently since their speeds vary from each other as they perform these important tasks.

For instance, hypochlorous acid oxidizes the organisms in several seconds, while the hypochlorite ion takes about 30 minutes.

Additionally, HOCl and OCl- levels will always depend on the hot tub’s pH level. If your hot tub has a high pH, the low presence of HOCl will make it hard for the tub to be cleaned quickly.

This dictates more time to clean the hot tub. The appropriate level of pH in the hot tub is between 7 and 8; 7.4 is ideal.

After the HOCl and OCl- finish cleaning your hot tub, they might combine with ammonia or another chemical or even broken down to become single atoms.

Consequently, the chlorine becomes harmless. If the hot tub is exposed to sunlight, the processes take a shorter time to complete, making the hot tub require more frequent chlorine top-ups.

Does Chlorine Have Any Side Effects On Humans?

Yes. Although chlorine has very beneficial properties that kill bacteria in water, it has several side effects that come as both a nuisance and annoyance to human beings.

Indeed, the side effects are hazardous. Most people find chlorine’s string distinctive smell to be unpleasant, even annoying. Indeed, this smell can be overwhelming to some people.

Additionally, chlorine causes itchiness to some skin types. It is also quite irritating to some skins. Again, many fabrics are negatively affected (through fading) by the hypochlorite ion.

This is more prevalent if you take too long before rinsing your swimsuit after leaving your hot tub.

If high amounts of chlorine gas over above your hot tub for extended periods, your breathing might be negatively affected.

Why Does the Chlorine in My Hot Tub Disappear?

Although some companies have sought to solve these problems by developing chlorine alternatives, none of the available alternatives can perform like chlorine when killing bacteria and cleaning your hot tub water.

 Another area where chlorine is unbeatable is its low price and the level of oxidation it performs.

Are There Ways I Can Maintain A Proper Chlorine Range In My Hot Tub?

Yes. It is possible to ensure that you maintain a proper chlorine range in your hot tub. Ideally, the role that chlorine plays in your hot tub care is insurmountable. Its level should be between 2 and 4 ppm.

To stay away from water problems in your hot tub, it is critical to practice routine water care. But this worthwhile routine might at times not work because of various factors.

For instance, if the number of people who use the hot tub is increased, the chlorine will seem to be used up at a faster rate.

On the other hand, exposure to more sunlight might also force you to add chlorine to your hot tub water more frequently.

It is recommended that you avoid using your hot tub if the chlorine levels are not in the correct range. It is therefore advisable to always treat the water after you are done enjoying your soak.

If you regularly take care of the water, you will effectively steer away from water chemistry issues. Hot tub owners must ensure that they rinse the filters monthly in addition to testing the water.

Despite treating your hot tub and working on all issues, there are times that you might realize that it won’t stay on the range, no matter how hard you try.

Normally, this results from an underlying problem. If your chlorine levels seem to diminish too soon, it is needful first to test the possibility of an underlying problem in your hot tub.

Look for issues along the lines of sunlight, biofilm, and dirty water since these can render water sanitization ineffective.

Will Shocking My Hot Tub Water Address PH Problems?

Yes. When you shock your hot tub water, you practically raise chlorine levels beyond the standard recommendation for a short time. During hot tub shocking, organic compounds are removed from the water.

In addition to this, bacteria are also killed and remove chloramines and bromines from the water. Also, the bromides are reactivated in the hot tub for cleaner water.

You might find it helpful to shock your hot tub water once every other week. However, you can increase this frequency if you have a hard time keeping chlorine levels within range.

Again, it is needful to tackle biofilm. If you have noticed a film on your spa’s surface and the pillows are slimy, you might have a biofilm problem that will hinder the effectiveness of normal chlorine amounts in your hot tub.

Caused by bacteria and microorganisms sticking on the surface of your hot tub, this is resistant to chlorine.

Indeed, the presence of biofilm is a precursor to chlorine’s “disappearance” from your hot tub. The reason for this is chlorine continuously works to eliminate the biofilm.

Biofilm sticks on the hot tub shell, in addition, to build upon your hot tub’s plumbing. It is not easy to eradicate the effect of biofilm without using an enzyme product.

This is handy in the removal of build-up and contaminants from your hot tub. It is critical to follow the manufacturer’s instructions if you wish to get good results.

Will Appropriate Hot Tub Water Care Reduce Chlorine Loss?

Yes. The effectiveness of the chlorine in your hot tub depends on how well you take care of the hot tub’s water. For instance, taking care of the temperature in your spa is a great way to ensure that chlorine levels are maintained.

As long as you are not using the hot tub, it is advisable to always lower the temperatures to somewhere below 100 degrees. This is because temperatures affect chlorine’s effectiveness.

Chlorine will evaporate at a faster rate when the water temperature is above 100 degrees.

While lowering water temperatures below 100 degrees is handy in maintaining your water chemistry, it will also lower the energy you use.

This will make the venture cost-effective. Modern hot tubs come with Wi-Fi module compatibility.

Therefore, you can add the Wi-Fi module as it will enable you to control the operations of your hot tub from your phone.

It is also advisable to ensure that your hot tub does not encounter direct sunlight. This is because the sun’s Ultra Violet rays are destructive to the chlorine in your water.

While you might feel nice soaking in the full glare of the sun on a crisp fall day, the UV rays can cause your hot tub’s chlorine levels to drop significantly and at a faster rate.

It is therefore recommended to consider erecting a shade if your hot tub is located outdoors.

Although a covering might work while the hot tub is not in use, there is no way it will be of any use when you are soaking in your hot tub.

Therefore, an offset umbrella or a sunshade might be the way to go. This is quite effective in filtering the sun while it doesn’t deny you the outdoor privileges you sought when installing your hot tub outdoors.

Do I Need To Maintain My Hot Tub?

Yes. Proper maintenance of your hot tub significantly affects the chlorine levels. It is recommended to ensure that you regularly test your hot tub water.

You might find the use of test strips your best option in this activity. This should be done once a week, at a minimum.

The appropriate free chlorine level is about 3 to 5 parts per million. Peradventure you find that the levels are higher, it is best to allow the hot tub to stay uncovered for a few days.

Since the sun has a way of removing chlorine from water, the levels will definitely come down.

Do Hot Tubs Lose Water Over Time?

However, you might not want to wait that long before you can use your hot tub. I will come to what you can do in such a case later in the article.

Well, if, on the other hand, the chlorine level is below the recommended range, it needs to be brought up.

To increase chlorine and raise the level in your hot tub, it is advisable to ensure that the chlorine you have is appropriate for hot tub use.

The best type of chlorine for such use is Sodium dichlor, as its pH is neutral, not necessarily requiring any chlorine stabilizer.

It is necessary to switch on the hot tub to have water circulation from the jets. This will come in handy when it comes to the circulation of the additional chlorine.

While the water needs to be on during this process, ensure that you have the air turned off to encourage chlorine gases to escape.

It is critical to understand exactly how much chlorine you need to get to the required chlorination level.

This needs to be calculated by measuring two teaspoons for every 200 gallons of hot tub water. The chlorine should be added to a bucket and allowed to dissolve.

After this, it needs to be poured into the hot tub, after which the hot tub needs to run for about two hours.

Once this time elapses, take time to check what free chlorine levels are available in the hot tub.

If necessary, you will have to add more chlorine, repeating the process as much as needed.

After subsequent chlorination in your hot tub a few times, you will quickly understand how much additional chlorine might be required in a week.

On the other hand, chlorine can be used in a hot tub, shocking, as already insinuated. The starting point will be checking the water’s pH levels.

Adjustments need to be done as appropriate. As you endeavor to shock your hot tub, remember that the pH level must be around 7.2 to 7.4.

You will need to turn on the water jets, leaving the air off as pointed above. Like in the above procedure, you will also need to calculate the quantity of chlorine you require in the hot tub.

Remember that your ultimate goal is to raise the chlorine level to about ten ppm temporarily. To shock a hot tub, you will need about 2 ounces of chlorine per 500 gallons of water.

When you are ready, dissolve the chlorine (after determining the correct quantity through calculation) in a small water container.

After it dissolves, add this water to your hot tub and turn off the hot tub for a few moments. Uncover the hot tub for about 30 minutes, and then check chlorine levels.

If the levels are beyond 5 pmm, it is not safe, and you will need to repeat the process until you achieve this.


Chlorine disappears from your hot tub as it performs its work. Since chlorine disintegrates when cleaning your spa and killing bacteria, it decreases over time, and you will find yourself with no option but to add more.

However, there are other instances when chlorine might disappear without doing its work. One of these instances is when your hot tub is exposed to sun rays.

Therefore, avoid direct sunlight by using a sunshade over your hot tub.


Hi! I' am Tom. I was a manager in one of the biggest stores for over 10 Years, am also an SEO by night. I don't like to call myself a blogger; they are very analytical, do email marketing, and know all SEO stuff. I faced many questions from customers about different products, and there was hardly any help on the internet. After learning all the things about these products as a manager the hard way, I decided to start a blog and help other people.

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