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Chlorine and Hot Tubs: A Comprehensive Guide

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Using a hot tub is luxurious, but it’s much nicer if you ensure your hot tub is safe and clean. Chlorine treatments are an essential part of keeping your hot tub clean. 

In this guide, I’m going to explain why chlorine is important, and provide you with some instructions on how much chlorine to use for your hot tub, whatever size it is. 

The Role Of Chlorine In Hot Tub Maintenance 

Chlorine sanitizes the water in your hot tub and prevents harmful bacteria and microorganisms from growing. It is an essential part of hot tub cleaning and should not be neglected. 

Without regular chlorine treatments, your hot tub can become a breeding ground for bacteria and fungi. This can cause some very serious health problems. Untreated hot tubs can be breeding grounds for Legionella pneumophila, which is the cause of Legionnaire’s disease. 

Understanding Hot Tub Water Chemistry 

As a hot tub owner, it’s important to have a basic understanding of water chemistry. Here are the most important things to know; 

  1. pH 
    Your water’s pH level is a measure of how acidic or basic the water is. The ideal pH level for hot tub water is between 7.2 and 7.8. 
  1. Total Alkalinity 
    Alkalinity represents how resistant the water is to changes in pH. The recommended range for your hot tub’s total alkalinity is between 80 and 120 parts per million (ppm). 
  1. Free Chlorine Level 
    The amount of free chlorine reflects how much chlorine is available to sanitize the water. The recommended range for free chlorine in a hot tub is between 3 and 5 ppm. 
  1. Combined Chlorine 
    Unlike free chlorine, combined chlorine has already reacted with organic matter to sterilize it and is no longer available to sanitize the water. The amount of combined chlorine should be kept to a minimum, – preferably less than 0.2 ppm. 
  1. Oxidizer 
    Oxidizer breaks down organic matter and disinfects the hot tub water. The most common hot tub oxidizers are chlorine shock and potassium peroxymonosulfate. 
Chemical Component Ideal Range 
pH 7.2 – 7.8 
Total Alkalinity 80 – 120 ppm 
Free Chlorine Level 3 – 5 ppm 
Combined Chlorine < 0.2 ppm 

Now that you understand the basics of hot tub water chemistry, let’s look at how much chlorine you need for your hot tub. 

The amount of chlorine you need to add to your hot tub will depend on the size of your hot tub and its current chlorine level. 

Too much chlorine can irritate your eyes and skin, and too little chlorine could lead to bacteria having the chance to grow.  You need to test your water and follow the instructions on your specific chlorine product to make sure that you are adding the right amount of chlorine.  Here are some guidelines to follow. 

  1. Chlorine Tablets 
    Tablets are the most common way for hot tub owners to add chlorine to their tub. The correct amount to add is typically 1-3 tablets per 500 gallons of water per week. 
  1. Chlorine Granules 
    Chlorine granules dissolve fast and can be added to the hot tub water directly. A tablespoon of granules is equal to about one chlorine tablet so the recommended amount of chlorine granules to add is usually 1-3 tablespoons per 500 gallons of water per week. 
  1. Liquid Chlorine 
    Liquid chlorine can be added directly to your hot tub, although it will not dissolve as quickly as tablets or granules. The recommended amount of liquid chlorine to add is typically 1-3 ounces per 500 gallons of water per week. 
  1. Sodium Dichlor Granules 
    Sodium Dichlor contains both chlorine and stabilizer. The recommended amount to add is 1-3 tablespoons per 500 gallons per week.  
Chlorine Type Dosage per 500 Gallons per Week 
Chlorine Tablets 1-3 tablets 
Chlorine Granules 1-3 tablespoons 
Liquid Chlorine 1-3 ounces 
Sodium Dichlor Granules 1-3 tablespoons 

*These are all general guidelines, and you should always refer to your particular chlorine product’s instructions before adding it to your hot tub. You should also regularly test your hot tub water to ensure that you are maintaining an adequate chlorine level. 

Can You Use Chlorine Tablets In A Hot Tub? 

Yes, chlorine tablets are the most common way to add chlorine to a hot tub. They are easy to use and are portioned out in exact amounts which makes it easier to add the right amount without having to measure it yourself. 

  • Make sure that the tablet has fully dissolved before anyone gets in the pool. 
  • Always test the chlorine levels in your tub before and after adding chlorine. 
  • If the chlorine levels in your hot tub are too high, you can adjust them by adding more water. 
  • You can but chlorine tablets at almost any pool or hot tub supply store, as well as most hardware stores. 

        Can You Use Pool Chlorine Tablets In A Hot Tub? 

        No, it is not advisable to use pool chlorine tablets in a hot tub. 

        This is because pool tablets are designed to be diluted by the large amount of water that a pool holds. If you used the same number of tablets in a hot tub as a pool the water would have far too much chlorine in it. 

        You should use hot tub tablets and not pool tablets. 

        Factors To Consider When Adding Chlorine 

        Before you add chlorine to your hot tub, consider the following factors: 

        1. Hot Tub Size 
          This is the biggest factor to consider. The larger the hot tub, the more chlorine will need to be added in order to reach the recommended levels. 
        1. Frequency of Use 
          Regular use of your hot tub will mean that you need to clean and disinfect it more often. Regular use introduces bacteria and dirt. 
        1. Water Temperature 
          Higher water temperatures can reduce the effectiveness of chlorine so you may need to add slightly more. 

        How To Add Chlorine To Your Hot Tub 

        Follow these step-by-step instructions for optimal results when adding chlorine to your hot tub (unless the instructions state otherwise): 

        1. Test the Water 
          Always test your water before adding chlorine. This will give you a baseline of your chlorine levels and let you know how much you might need to add. 
        1. Prepare the Chlorine 
          Measure out the correct amount of chlorine for your hot tub size. 
        1. Add the Chlorine 
          Add the chlorine to your hot tub. Add the prepared chlorine to your hot tub water. I find it best to add the chlorine near one of the hot tub jets so that it can help distribute it. 
        1. Turn on the Jets 
          Turn of the jets to circulate the chlorine through the water. 
        1. Wait 
          Wait until the chlorine is fully dissolved before getting in the hot tub. The recommended wait time is usually around 20 minutes, but I always wait at least 30. After 20 minutes the chlorine levels should be high enough to kill any bacteria in the water. 
        1. Retest the Water 
          I always like to test the water again before getting in to make sure that there is not too much or too little chlorine in the water. If there is too much, add more water to dilute it. If there is too little, repeat steps 1-5. 

        Recognizing High Chlorine Levels In Your Hot Tub 

        As well as testing the water, you should know how to identify high chlorine levels in your hot tub. Common signs of high chlorine levels are: 

        • A strong chlorine smell 
        • Stinging or itchy eyes 
        • Skin irritations, such as rashes or dryness 
        • Corrosion or deterioration of hot tub parts like the cover and headrests 

        If you suspect that your hot tub’s chlorine levels are too high, you should use a test strip to check. If they are higher than 1 and 3 parts per million (ppm), add more water to dilute the amount of chlorine. 

        Enjoy A Clean, Sterile Hot Tub 

        Disinfecting your hot tub helps keep you safe and keeps your hot tub in good condition, prolonging its lifespan and maintaining its value. Remember to always check the instructions on your particular chlorine product before adding it and always wait at least 20 minutes for it to properly dissolve before getting in the hot tub.