Spas and hot tubs are like swimming pools in that they need chemicals to control the level of algae and bacteria in them. Bromine is the preferred hot tub sanitizer but is more expensive than other options. To cut costs, hot tub owners often use chlorine instead. It's important to maintain the correct amount of chlorine in your hot tub, just as it is in a pool. If the chlorine level is too low, the spa won't be sanitary. If it's too high, the excess chlorine will dry out your skin. A weekly check of your spa lets you maintain the proper chlorine levels on an ongoing basis. You will need to shock your hot tub, however, after heavy usage and when opening it for the season.
Test your spa water at least once a week using test strips. Your free chlorine level should be between 3 and 5 parts per million. If it is higher, leave your hot tub uncovered, and simply wait for the chlorine level to come down. This may take a few days. If it is too low, follow these steps to add chlorine.
Verify that you have the correct type of chlorine for spa use. Sodium dichlor works best in hot tubs, because it has a neutral pH and does not require the use of a chlorine stabilizer.
Turn the hot tub on. The water from the jets will help circulate the chlorine you will be adding. You want the water jets on, but leave the air off, because this encourages chlorine gases to escape.
Allow the hot tub to run for two hours and then check the free chlorine levels again. Add more chlorine if needed, and repeat the process. After chlorinating your spa a few times, you'll get a good idea of how much chlorine to add each week.
Check the water's pH level and adjust it as necessary. When shocking a spa, the pH level should be between 7.2 and 7.4.
Turn your hot tub's water jets on, but leave the air off.
Calculate how much chlorine (sodium dichlor) you need. The goal of shocking is to temporarily increase the free chlorine level to 10 ppm. Shocking a hot tub requires about 2 ounces (4 tablespoons)of chlorine for every 500 gallons of water.
Dissolve the desired amount of chlorine in a bucket of water, and then add the water to your hot tub. You can turn the spa off a few minutes after adding the chlorine, but leave it uncovered for at least 30 minutes.
Do not use your hot tub until the chlorine level drops back down to 5 ppm.