For the free chlorine in your hot tub to be low means that there might be a high level of combined chlorine in it. A smelly hot tub is a clear indicator of the chloramines present in the hot tub.
Combined chlorine is chlorine that has reacted with other compounds like ammonia. These reactions render chlorine ineffective. To make them effective again, you need to break the bond and free them from the compounds.
The process of freeing up these chlorine molecules is known as shock treatment. To raise the free chlorine in your hot tub, you need to shock the spa. Shock treatment helps you raise the level of free chlorine in your pool instantly.
But that’s not always the case. Your free chlorine can also escape the spa through the water vapor leaving the tub. In that case, you may not need the shock treatment to raise the free chlorine level.
Adding chlorine sanitizer can help to increase the amount of free chlorine in the hot tub. In either case, the aim is to introduce new chlorine molecules into the hot tub to raise the free chlorine level to the recommended range of 1-3 ppm.
So, whether you use chlorine shock or chlorine sanitizer, ensure that the free chlorine level is effectively adjusted to the appropriate range.
What do I do if my free chlorine is low?
If the free chlorine in your pool becomes low, the first thing you need to do is stop using the hot tub. Once the free chlorine level becomes low, your spa becomes prone to bacteria attacks.
Remember that most of these bacteria and other microorganisms thrive in warm and moist environments. This means that your hot tub is a perfect habitat for them to multiply. If they are allowed, they can multiply overnight.
This makes the spa unhealthy for anyone to use. If you use a hot tub with low free chlorine content, you are risking your health. So, do your best not to use it.
The next thing to do is to identify the cause of the low free chlorine. It could be as a result of contaminants or exposure to sunlight. Using a DPD kit can help you determine this.
If the combined chlorine present in the hot tub is below 0.2 ppm, then the problem is not caused by contaminants. Leaving your spa open can cause the chlorine to deplete rapidly. It could be the cause.
Once you know the cause of the problem, the next step is to increase the free chlorine level to 1-3 ppm.
How do you increase free chlorine?
As we stated before, you can increase the free chlorine by adding chlorine sanitizer or by using shock treatment.
You use shock treatment when you temporarily need a high dose of chlorine in your spa instantly. Usually, you shock your spa once a week or when it is invaded by microorganisms, including bacteria and algae.
Chlorine sanitizer is used to maintain or regulate the free chlorine level in your pool. It releases chlorine into the water gradually and ensures that there is always free chlorine present in the hot tub.
If there is little depletion of free chlorine in the spa due to water evaporation, you can adjust the level using a chlorine sanitizer. You don’t use chlorine sanitizer when the spa has already been invaded by bacteria or algae blooms.
Whichever one you are using, the main aim is to raise the free chlorine to the appropriate range as soon as possible. Below are the sole steps for each of the methods.
How to add chlorine sanitizer to your hot tub
Since you have confirmed that the chlorine sanitizer level in your hot tub is low, follow the steps below to raise it.
- Buy the right chlorine sanitizer for your spa. Check where you will get sodium dichlor and use it for your hot tub. With sodium dichlor, you don’t need a chlorine stabilizer. So, it makes the whole process easier.
- Turn your spa on and make sure that the jets are working properly. The jets ensure that the chlorine is evenly circulated. The air needs to be off so that the chlorine doesn’t escape as gas.
- Determine the amount of chlorine to be added. For every 200 gallons of water, you need 2 teaspoons of chlorine sanitizer.
- Dilute the chlorine. You don’t have to pour the chlorine directly into the spa. Fill a bucket with water to about two-thirds full and add the chlorine to it. Stir to dissolve and pour it into the hot tub.
- Leave the spa to run for at least 2 hours before you test for chlorine level. Repeat the process if the chlorine level is still low.
How to shock your hot tub
Remember, you only shock your pool when you temporarily want to dose the hot tub with a high amount of chlorine. Below are the simple steps to follow.
- First, you need to check the pH level of the hot tub before you start. Chlorine is more effective in the pH range of 7.2 to 7.6. So, if the pH is not within this range, adjust it accordingly.
- Turn the jets on while leaving the air off. The jets help with proper circulation. Make sure the air is off because it can make the chlorine escape as gas.
- Determine the amount of chlorine you need to shock the spa. Usually, hot tubs require about 4 tablespoons of chlorine per 500 gallons of hot tub water. Remember, the aim is to increase the free chlorine level temporarily to 10 ppm.
- Add the chlorine to a bucket of water and stir until it dissolves. Pour the mixture into the hot tub and allow it to circulate.
- Wait for the chlorine to drop to the recommended range of 1-3 ppm before you test the water again.
How do you raise free chlorine without raising total chlorine?
Free chlorine and total chlorine are expected to be in the range of 1-3 ppm. If total chlorine is in the appropriate range while free chlorine is very low, it means that there is a high amount of combined chlorine in the hot tub.
I adjust the free chlorine, you need to shock the hot tub. The shock treatment will help to release the bonded chlorine molecules. This process does not affect the total chlorine if it is within the required range.
One thing you need to know is that both the free chlorine and total chlorine will go high. But with time, their level will drop to the recommended range.
Should free chlorine equal total chlorine?
Free chlorine should be equal to total chlorine when the chlorine has not been used or has not reacted. But once the chlorine starts reacting with other compounds in the hot tub, the free chlorine will drop because some of it will be converted to combined chlorine.
The combined chlorine is the reacted chlorine molecule in the hot tub that is almost ineffective at killing bacteria. As a result of this conversion, free chlorine is usually slightly less than total chlorine. However, the difference between free chlorine and total chlorine shouldn’t be more than 0.2 ppm.
If their margin becomes more than 0.2 ppm, it means that the combined chlorine in the spa is high and needs shock treatment.
Should I put chlorine in my hot tub every day?
If you don’t use your hot tub every day, there is no need to put in chlorine every day. However, you need to add chlorine 2-3 times a week and shock it at least once a week.
This routine maintenance will help to keep the spa free of bacteria and other microbes.
Can you use a chlorine floater in a hot tub?
Yes, you can use a chlorine or bromine floater in your spa. But you need to be very careful because it can cause a lot of damage to your pool if you don’t use it the right way.
If you don’t set it right, it can add too much chlorine to your pool. Or, it may not be able to add the required amount of chlorine to your pool, which will attract microbes to the pool.
If you must use it, you need to confirm with the manufacturer whether you can use it in your hot tub. Then follow the instructions strictly.
You can read this post to learn how to use a chlorine dispenser or floater.
Another thing you need to be doing is endeavoring to check the chlorine level regularly.
How do you shock a hot tub with chlorine granules?
If you are using chlorine granules, you will still use the steps illustrated above. The only difference is that you will be dissolving about 1 oz of chlorine granules in every 500 gallons of hot tub water.
Aside from that, every other step is the same. Make sure that the granules dissolve completely before you add the mixture to the hot tub.
Granules can easily drop to the bottom of your spa and damage it if you add them directly.
When should I add shock to my hot tub?
Add shock to your hot tub any time there are algae blooms. Even though your hot tub does not turn green, you need to shock it once you notice that the level of combined chlorine is high.
Moreover, you need to shock your spa once a week or at least once every two weeks.