How Long Does It Take To Lower Chlorine in a Hot Tub?

Chlorine is an essential part of maintaining a sanitized environment for you and your family. Hot tubs may become a breeding ground for pathogens that may affect your health and spread disease. However, chlorine comes with its own hazards, such as elevated free chlorine concentrations. 

In general it takes 24 to 48 hours to lower chlorine in a hot tub naturally. Diluting your tub water may save you time, but both methods are dependent on your chlorine levels. Neutralizers will reduce your chlorine in about 1 to 3 hours, and replacing your water will require a re-chlorination wait. 

Chlorine may affect your hair and skin in elevated doses and if your tub has high chlorine levels. There are several ways to lower your chlorine, depending on how urgently you need to use it. Read on to know the five ways to lower chlorine in your tub and how long you should expect to wait before soaking in those warm jets. 

How Long Should I Wait After Attempting To Lower the Chlorine?

You should wait 24 to 48 hours after attempting to lower the chlorine for it to dissipate in your hot tub, but this isn’t an exact science. Dissipation time is affected by tub size, surface area, temperature, pH, and initial chlorine levels. You should test your free chlorine levels to be safe. 

Alternatively, you can add fresh water to your hot tub to reduce the chlorine levels and reduce your waiting time.

As little as 30 ml (1.01 oz) hot tub neutralizers can reduce your chlorine or bromine levels of 1,000 L (264. 17 gals) of water by 1ppm. However, the wait time may vary between an hour to three hours. You may partially dilute or completely replace your hot tub water if you’re not willing to wait. 

However, you would need to re-chlorinate your tub to raise the chlorine levels. 

5 Steps To Lower Chlorine in a Hot Tub

Let’s now talk about how to lower the chlorine levels in your hot tub. If you follow these steps, you will have better results.

1. Lower the Chlorine by Evaporation

One of the most straightforward ways to lower the chlorine levels in your hot tub is to play a waiting game. Chlorine is a gas at room temperature and in water and is known as a volatile solute in water. This volatile state means that chlorine molecules diffuse in your hot tub water and will escape into the air over time.

You’ll need to remove your hot tub’s cover and keep the water at a warm level to increase the dissipation process. 

2. Lower the Chlorine by Dilution

You may dilute your hot tub water with fresh water by increments, measuring between changes to determine if your chlorine levels are safe. If your hot tub is full, you may need to backwash your water several times while increasing the amounts of fresh water in the tub. 

Dilution is a simple way to decrease your waiting time but may not solve excessively high chlorination levels. 

3. Drain Your Tub and Replace Your Water With Fresh Water

If you’re due for a water change already, you might want to start from scratch by draining your hot tub and replacing it with fresh water. If you don’t want to pay for expensive chemicals or wait for the chlorine levels to drop naturally, this may be your best option. 

However, you’ll need to re-chlorinate the freshwater to make your tub sanitized and safe to use. 

4. Use a Neutralizer To Drop Your Chlorine Level

Sodium thiosulfate or Na2S2O3 is the base ingredient in many of the chlorine neutralizers on the market. It is a compound that comes in a white or colorless pentahydrate that dissolves rapidly in water. 

The chemical neutralizes by forming sodium hydrogen sulfate and sodium bisulfate, which are inactive salts.

The use of a neutralizer comes with a caveat in that it may eliminate all your chlorine/bromine if you overdose and may render your tub unsanitary. You should always follow the instructions carefully and test that your chlorine levels are at a high enough level to ensure your tub stays sanitized. 

5. Vitamin C Dechlorination

Vitamin C is fast becoming a new and viable solution in chlorination neutralization. It doesn’t lower oxygen levels as chemical neutralizers do and is safe for human and aquatic life. Vitamin C neutralization takes two forms:

  • Ascorbic acid
  • Sodium Ascorbate

What Are the Ideal Chlorine Levels in a Hot Tub?

The Center for Disease Control and Prevention (CDC) recommends that your pH be between 7.2–7.8 and a free chlorine concentration not below 3 parts per million (ppm) in hot tubs.

Due to the variable factors that affect the speed of chlorine breakdown in your hot tub water, the safest way to ensure your safety is to test your free chlorine levels. You have three options to test your chlorine levels as follows.

Chlorine Strips

Chlorine strips are quick and easy to measure your free chlorine levels, but they’re not the most accurate. You should ensure that your test distinguishes between free and combined chlorine levels. Free chlorine is the active amount of chlorine in your tub, while combined chlorine measures the active and residual levels of chlorine in the water.

Take a Sample of Your Hot Tub Water to a Professional

Many hot tub companies offer professional services for their clients in their stores. Take a sample of your water to measure your free chlorine accurately. Typically they’ll charge a small fee for their services, but you’re guaranteed a professional measurement. 

They can also offer advice on how to correct your chlorine levels. 

Use a DPD Test To Measure Your Chlorine Levels

DPD is a powder or tablet composed of N, N diethyl-p-phenylenediamine, which changes color to pink when in contact with chlorine. Once you have added the chemical to a sample of your tub water, you may measure your chlorine levels according to the color chart. The DPD test tends to be more accurate than the test strip method.


Hot tubs are a coveted luxury, and you should ensure that your tub is sanitized and free from elevated chemical levels. Depending on your urgency, there are several safe and easy methods to ensure the safety of yourself and your family. Testing your chlorine levels repeatedly in any chosen solutions is essential for a safe and happy soak.

Jed Arnold

Jed spent every year from the ages of 15 - 22 as a Lifeguard (Red Cross) and ages of 17 - 22 as a Certified Pool Operator (CPO). Between working for over a dozen facilities and owning a pool, he carries over a decade of pool experience.

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