1. Most spa manufacturers recommend a Calcium Hardness (CH) level for your spa of 150-200 ppm. We do not, however, recommend adding calcium to your spa if your spa water is above 100 PPM or if your incoming water has a very low level of calcium hardness.
2. Calcium Hardness is a measure of the total amount of dissolved calcium in the water. It is believed that calcium helps control the corrosive nature of water, but calcium has a tendency to precipitate (fall out of suspension) at high temperatures and high pH levels.
Warning: When calcium falls out of suspension, it can collect on the heater and pump and shorten their life.
3. Any natural corrosiveness in the water can be alleviated by maintaining a slightly higher Total Alkalinity Level.