It is estimated that there are nearly 7 million hot tubs, also known as spas, in use in the United States. Tubs come in a variety of sizes and shapes. Some are small enough for only two people, others large enough for a party. High temperatures (104 degrees maximum) and water offer a friendly place for bacteria to grow so tubs need to be sanitized regularly to keep them clean.
Chlorine is a common sanitizer for hot tubs and also used to “shock” the water as needed to keep it clear and odor free. Some manufacturers recommend shocking once a week. The chlorine preparation known as Dichlor, usually in granular form is intended for hot tubs since it is faster dissolving than Trichlor used in swimming pools and often sold as a liquid. According to the hot tub industry, a common mistake is using swimming pool chlorine to sanitize your spa parts. This can harm the tub and render its warranty invalid. Follow manufacturers directions on the brand of Dichlor used and store chemicals in a cool, dry and well ventilated area away from children.
Once your tub is filled, maintain the chlorine levels at one to three parts chlorine per million parts water. Wait several hours after adding chlorine to test the levels. If the water is checked too soon, the chlorine may not have had time to disperse adequately. The water is tested using a commercially available test kit. The strips are placed in a sample of water from the hot tub and then compared to the color chart on the back of the bottle. Initially, add one half teaspoon of chlorine per 100 gallons of water and then check the chlorine levels. After using the tub, more chlorine should be added. When the tub is not in use, the addition of chlorine three times a week is sufficient.
Another option for sanitizing is the use of a slow release method. This may be a floating dispenser or a mineral cartridge installed into the filter. Depending on the brand and use of your tub, mineral cartridges need to be replaced about every four months. The makers of these devices claim that less chlorine is needed when they are in use.