The measurement of minerals in your water including calcium and magnesium is referred to as water hardness.
Spas and swim spas should have some level of hardness. If your spa water does not have enough calcium, the water will draw minerals, including copper, aluminium and iron form spa parts such as spa heating elements and spa pump seals. This results in equipment corrosion and failure.
If however there is too much hardness, you will see scale formation on the spa's interior and the water will take on a cloudy appearance caused by calcium carbonate. The surfaces of your spa may feel gritty to the touch and you will develop a build up of scale on spa surfaces including pumps and heaters.
What should the calcium reading be?
Ideally the calcium level should be between 100- 200 PPM's for acrylic spas and swim spas and 250-450 PPM's for plaster finish. Test your spa water using the correct test strips for your system.
Some potential problems if calcium levels go unchecked:
Hardness too low.
The corrosion of metallic components in spa equipment and unwanted foam. To raise the hardness of my spa water, use a calcium increase such as the Zodiak calcium increase. Hardness is too high The formation of scale on spa surfaces and cloudy water. To lower water hardness, use a water softener such as Zodiak Spa Silk water softener which makes the spa water and surfaces feel silken. It also has a faint Rose scent.