Scale found in pools and spas is usually characterized as that ugly and rough, chalk-like buildup that often occurs along the waterline. This can be visible on beautiful water features, or may even cover the entire surface in a sandpaper-like crust. Scale is not only unpleasant to look at, but can also make surfaces rough to the point of being dangerous. Scale can also contribute to many other negative factors that impact the overall wellness of the water. Scale (calcium carbonate) has been an ongoing problem in many pools and spas due to the fact that over time minerals precipitate (fall out of solution) and settle, becoming a solid on the surfaces. There are many different situations that can cause this process to take place, but the most common is when the water has a high calcium hardness level as well as a high pH. Quite often the first sign of problems is cloudy water. This is not just an unsightly problem. Calcium carbonate can cause skin abrasions, snagged bathing suits, and can clog filters. When scale builds up in piping, circulation is reduced and pressure increases.
Calcium carbonate has been recognized in the pool and spa industry for years, however, recently another type of calcium has become more common: calcium phosphate. This form of scale is created when phosphates combine with calcium in pool and spa water, particularly in heated water. This combination is an insoluble white scale that is complex and difficult to remove with chemicals. When calcium phosphate falls out of solution, it can often resemble DE or sand, feel gritty to the touch, and often gathers at the bottom of the pool or spa. Oftentimes, it is easiest to vacuum calcium phosphate scale to waste and follow up with a phosphate removal as needed.
When it comes to any type of scale whether it is calcium carbonate or calcium phosphate, prevention is best. Scale is difficult to remove once it has formed. Plan to use a PHOSPHATE FREE stain & scale product such as Natural Chemistry’s Scalefree for pools or Spa Stain & Scale for spas and maintain phosphate levels below 100ppb to help prevent scale accumulation. This is especially important for new plaster finishes, and pools using a salt chlorine generator system.