Relaxing in a spa is probably the best way to spend free time and let the worries of the world melt away. Trying to maintain that hot tub should be just as easy. When talking about water, you inevitably have to get into water chemistry. Thankfully, learning the basics for running clean, crystal clear hot tubs is a quick and easy lesson. After learning about sanitizers and understanding the concept of water hardness and pH, maintaining a hot tub becomes a good habit.
Even if you already own a pool, the water in a spa is a little different to maintain, but the same general concepts apply. The biggest difference is the water temperature, since hotter water is a better environment for bacteria and it will also open up the pores on our skin, thus lowering our tolerance to these bacteria.
Sanitizers for portable spas are similar to the ones used in swimming pools. The most common types are chlorine and bromine. Adding them to the water is a habit that must be followed in order to kill bacteria inside the water. Test strips can be purchased to measure the sanitizer level in the water; the strips are simple to use, typically they only need to be dipped in the water and then they will change color according to the sanitizer concentration.
A good level for chlorine is between 1.5 and 3 and bromine 3 to 5. Higher numbers will leave out an odor, and lower amounts will not effectively kill bacteria, so staying within the above range is ideal.
Just as calcium is good for our bones, it is good for hot tub water as well, but only in the right dose. Hard water, or a high amount of calcium and other minerals, will give the water a cloudy appearance and will form scale in the tub and on the equipment. Low hardness will actually harm the tub's pump by pulling out minerals from the pump parts and into the water.
The ideal range is for calcium is between 100 and 250 for acrylic hot tubs, and 250 to 450 for plaster, which can be measured using test strips. Calcium can be added to water with a booster product, but lowering calcium is more difficult. It is best to fill hot tubs with water that has been run through a softener filter before it fills the spa, more calcium can always be added if it is too low.
pH is a measure of how acidic or basic the water is; acids are low in pH and bases are high in pH, neutral water has a pH of 7. The ideal pH range for hot tubs is 7.2 to 7.8 and can be measured with pH paper or electric meters. Lower pH means that the water is acidic and will damage the spa and irate skin, and a higher pH will cloud the water as well as irritating the skin. pH is changed by added a "pH Up" or "pH Down" to get the value just right. It might take a few tries, but once you get the handle on how the pH reacts to change, it will be easy to control.
That's it! In just a quick article you learned the basics of spa water chemistry without getting a four year degree.