There is an unique difference between a pool and spa, it is very important that you maintain your spa with chemicals specifically formulated for spa/hot tub use. It is important to realize that a spa is different from a pool because you are dealing with water that is heated between 98-104 degrees F, much warmer than a swimming pool. The ratio of people to the amount of water in a spa is much greater. The heated water and higher bather load ratio can result in spa water problems due to a great deal of residual soaps, deodorants, perfumes and other cosmetics. Also, there are natural body oils that are released into the spa water and  cause other organic contaminants.

Testing the Alkalinity:
The total alkalinity test measures all of the alkaline or base materials in the water. Total Alkalinity acts as a buffer to stabilize the pH. The total alkalinityfor a spa is between 80ppm and 120ppm. If the total alkalinity is too low, the water has very little buffering capacity and the pH will become erratic. A high total alkalinity means that the water has too much buffering capacity and the pH will be very difficult to change. For this reason it is best to adjust the total alkalinity
first.

Testing the pH Levels:
The pH test will tell you if your water is acidic or alkaline (base). The pH is measured on a 14 point scale with 7 being neutral. A pH reading of below 7 would be considered acidic and one above 7 would be alkaline. The ideal pH fora spa is bewteen 7.2 AND 7.8. If the pH is lower than 7.2 the water could start to dissolve the metal in your spa equipment and also cause irritation to your eyes and skin. A high pH above 7.8 could result in deposits of Calcium or scale on the spa and equipment.

Cleaning/Changing Filters:
Keeping filters are important for hot tub water quality than your filtering system.  A dirty, worn-out filter will fail at its job of trapping contaminants, and put strain on your spa's pump. Clean your filters with every water change. Use the filter rotation method, while your dirty filter is soaking in cleaning solution, replace it with a clean dry spare. With this system, you will never have to wait to use your hot tub, and your filters will last longer. After about a year of use, the pores in the filter media lose filtration ability and the filter should be replaced.