How Much Chlorine To Add to Your Hot Tub the First Time You Use It

Michael Keenan


Hot Tub Water Chemistry

You’ve finally got your brand-new hot tub set up and you’re ready to dive in. But hold on! There’s a crucial step you can’t overlook – adding the correct amount of chlorine.

Navigating the world of hot tub water balance can seem daunting, but don’t worry, it’s simpler than you might think. The right amount of chlorine keeps your water sparkling clean and safe for use.

Too little and you risk bacteria build-up; too much and you could be facing skin and eye irritation.

This handy guide will walk you through the dos and don’ts of adding chlorine to your hot tub for the first time. By the end, you’ll have a clear understanding of why chlorine is essential for your hot tub, how much to add, and how to maintain ideal levels.

So, let’s get started, shall we?

adding chlorine to a hot tub the first time

Key Takeaways

  • Regular chlorine maintenance is essential to keep hot tubs free of bacteria and contaminants.
  • The initial chlorine dosage for a hot tub will depend on the chlorine product you use and the volume of your tub.
  • It is important to test the chlorine level and adjust the dosage as necessary to reach a level of 3 to 5 ppm.

Why Add Chlorine to Hot Tub Water?

All hot tubs need to have an effective sanitizer to keep the water safe and free from contaminants. Chlorine is the most popular hot tub sanitizer – although there are alternative sanitizers. More on alternatives below.

There are several advantages of using chlorine in hot tubs, but most importantly, it provides a barrier against harmful organisms that can spoil your experience and potentially cause health issues.

Despite common misconceptions, chlorine doesn’t harm your skin or eyes when used correctly. It plays an integral role in sanitizing hot tubs, making your spa a haven of relaxation and cleanliness.

For a head-to-head comparison check out my article Chlorine vs Bromine as a hot tub sanitizer. Some useful info in there.

chlorine at the side of hot tub

Different Types of Chlorine and Their Recommended Dosages

There are many different types of chlorine available for hot tubs, and each type has its own recommended dosage. It is important to use the right type and amount of chlorine so that your hot tub stays clean and healthy.

Here are some of the most common types of chlorine and their recommended dosages.

  • Chlorine Tablets: Chlorine tablets are the most popular type of chlorine for hot tubs, and typically contain either 90% or 99% trichlor. When using chlorine tablets, it is recommended to start off with 3-6 tablets depending on the size of the hot tub, and then add more tablets as needed. The tablets should be evenly distributed in the hot tub.
  • Chlorine Granules: Chlorine granules are small pellets of chlorine that can be added directly to the water. The recommended dosage for chlorine granules is 2-3 tablespoons per 500 gallons of water (approx.).
  • Chlorine Sticks: Chlorine sticks are similar to tablets, but come in a longer form, making them more suitable for larger tubs. The recommended dosage for chlorine sticks is 1-2 sticks per 500 gallons of water.
  • Liquid Chlorine: Liquid chlorine is a solution of chlorine that is added directly to the water. The recommended dosage for liquid chlorine is 1-2 ounces per 500 gallons of water.

These figures are a general guide – the product you buy will have the exact quantities they recommend. No matter which type of chlorine you use, it is important to follow the manufacturer’s directions for proper use.

It is also important to regularly test the chlorine levels in your hot tub to ensure that the correct amount is being used and that the hot tub remains safe to use.

chlorine tablets for a hot tub

What About Hot Tub Starter Kits?

Hot tub starter kit options are a great way to ensure you have everything you need from the get-go. They often include chlorine or bromine, a pH adjuster, a test kit, and a guide to help you avoid common mistakes when adding chlorine.

If one is included with your hot tub when you bought it, use it. If not I wouldn’t really buy a starter kit. You’re going to be using these chemicals on an ongoing basis so you might as well buy the products you want to use.

My main section on water chemistry for hot tubs has some great information to keep you right about the chemicals you’ll need to use. Have a read!

How Much Chlorine to Add to a Hot Tub First Time?

When setting up your spa for the first time, it’s important to get the chemical balance right. You’ll probably read some people recommending that you add extra chlorine to the water when filling it up for the first time. It’s really not necessary.

The goal is to get the chlorine levels settled at between 1ppm and 3ppm – 3ppm of chlorine is the ideal level. It doesn’t matter if it’s the first time you’ve filled your hot tub or the 100th!

It’s simpler to add extra chlorine later on, instead of trying to decrease the chlorine level if you added too much!

So, stick to the manufacturer’s guidelines for dosage rates. Remember the dosage guide above? The exact amount of chlorine will depend upon the volume of your hot tub and the type of chlorine product you choose.

Adding Chlorine to Your Newly Filled Hot Tub

Again, whether it’s the first time or the 100th, the process is the same for adding chlorine to a freshly filled hot tub. Of course most of the time you’ll simply be topping up your chlorine levels by testing and adding the required amount to keep levels at around 3ppm.

How to Add Chlorine Granules

Carefully read the directions on your chlorine container. Measure the quantity suggested by the manufacturer for your hot tub’s size. Once the tub is filled, slowly pour these granules directly into the hot tub.

Let the water circulate for about 20 minutes so that the sanitizer can spread out. Finally, test the water to check if the sanitizer levels are correct. If needed, make some adjustments.

Adding Chlorine Tablets to a Hot Tub

Use the number of tablets suggested by the manufacturer for your hot tub’s size. Insert the chlorine tablets into the chlorine dispenser/feeder.

If the feeder has adjustable settings, modify them according to the instructions provided by the manufacturer to regulate the sanitizer release. Immerse the feeder in the hot tub water to remove air and help it float steadily.

Over the next few days, test the water to make sure it has the right sanitizer levels. If needed, make some adjustments.

Using Liquid Chlorine

Once your hot tub is filled with water, measure the amount of liquid chlorine according to the size of your spa. Simply pour it into the water and allow it to circulate for about 20 minutes. Test the water and adjust if needed.

Always, always test your hot tub water before getting into it!

Added too much by mistake? I have guides on reducing chlorine levels in a hot tub and then how to lower bromine levels – if bromine is your sanitizer.

chlorine feeder in a spa

How Long Should You Wait After Adding Chlorine to Your Hot Tub Before Using It?

If you are adding chlorine as part of your regular maintenance then wait about half an hour before using the tub. As always, test the water before you go in!

If you are adding chlorine for the first time or have just refilled your tub, you should wait at least 1-2 hours depending on the water temperature and circulation.

This duration allows the chlorine to fully dissolve and sanitize the water. During this time, test chlorine levels to ensure they reach the recommended 3 ppm.

How Often to Add Chlorine to a Hot Tub?

So, you’ve added chlorine to your hot tub for the first time after filling it. The levels are perfect – you’re done! Not quite. You see the chlorine sanitizer is going to break down over time.

Chlorine oxidizes contaminants, breaking them down from the inside. However, during this process, chlorine changes into a by-product called chloramines.

Chloramines are responsible for the unpleasant smell, stinging sensation, and dryness often associated with chlorine, and they also lower its cleaning effectiveness.

To keep your sanitizer working effectively, you need to add chlorine regularly, typically every week. Topping up the chlorine as needed.

To keep your hot tub’s water sparkling and safe, regular monitoring and adjustment of chlorine levels is necessary. You should test chlorine levels at least once a week (more if it gets a lot of use) to ensure a level between 1 to 3ppm for optimal sanitation.

Simply test the water and add chlorine as recommended to increase the levels to 3 ppm. Adding chlorine in the evening when the hot tub is not in use is the best time to do it.

If the chloramine levels become too high and chlorine cannot manage it alone, you can use a method called “shocking” to cleanse your hot tub. Shocking should also be done periodically to maintain clear and clean water.

Read next: Can too much chlorine damage a hot tub? It can but read to find out how.

What Does It Mean to Shock a Hot Tub?

After discussing how often to add chlorine to your hot tub, it’s vital to understand another key term in hot tub maintenance – shocking a hot tub. Shocking involves adding a high dose of sanitizer, usually chlorine or non-chlorine shock, to eliminate contaminants, bacteria, and chloramines.

I have a whole section about how to shock a hot tub, I also cover how often to shock and then how long to wait after shocking your hot tub. Lastly, did you know you can over shock your hot tub – well you can!

Read those for all you need to know.

What Are Alternatives to Using Chlorine in a Hot Tub?

If you’re not keen on the smell or potential skin irritation from chlorine, there’s a variety of alternatives you can consider for sanitizing your hot tub.

One popular choice amongst these alternatives to chlorine in hot tubs is bromine. When comparing bromine and chlorine in hot tubs, bromine is less harsh on the skin and is more stable in hot water. However, bromine is slower-acting.

If you’re interested in natural options for hot tub sanitization, consider mineral sanitizers. They work in conjunction with a small amount of sanitizer to effectively kill bacteria.

The benefits of non-chlorine sanitizers include lower skin irritation and a more pleasant aroma. However, they may require more regular maintenance checks. Always weigh the pros and cons of using non-chlorine sanitizers before deciding.

Frequently Asked Questions

How does the size of the hot tub affect the amount of chlorine needed?

The size of your hot tub directly impacts chlorine concentration. Larger tubs require more chlorine. Size calculations, chlorine types, and tub materials all affect chlorine’s effectiveness.

Can I use chlorine tablets instead of granules for my hot tub?

Yes, you can use chlorine tablets instead of granules for your hot tub. Consider tablet longevity, dosage differences, storage convenience, and dissolution rate. However, also compare costs as tablets can be more expensive.

Is it safe to add other chemicals to the hot tub water along with chlorine?

Yes, you can add other chemicals alongside chlorine – but don’t add them together at once. Just check manufacturer guidelines to avoid adverse chemical interactions. Ensure each chemical dissolves before adding the next.

What are the potential risks or dangers of not using enough chlorine in the hot tub?

If you don’t use enough chlorine in your hot tub, you risk bacterial infections, skin irritations, and respiratory issues. Poor water clarity can also occur, and corrosion risks increase due to uncontrolled contaminants.

To Sum Up

In conclusion, it’s crucial to add the right amount of chlorine to your hot tub, especially when setting it up for the first time. Regular testing, maintenance, and possible pH adjustments are key to keeping your hot tub clean and safe.

Don’t forget, there are also alternatives to chlorine and hot tub starter kits to make the process easier.

Remember, a well-cared-for hot tub makes for a more relaxing experience.

michael keenan author

Author - Michael Keenan

I'm Michael Keenan the owner and creator of the Outdoor Care Guide. I'm a trained horticulturist with over 30 years of experience in pool care, plant care, and landscape care! Seemed like a good idea to share - I think I can make your life easier and save you some time and money!