Water Chemistry 101
What You May Not Know About Your Pool Water
What is pH?
pH is the term used to refer to the degree of activity of an acid or base (alkali) in the water. It is the most important chemical factor to be maintained in swimming pools. pH is measured on a scale from 0 to 14 with 7 being neutral. Pool water pH is best when kept in the range of 7.2 to 7.8.
What is Alkalinity?
Total alkalinity refers to the ability of the pool water to resist a change in pH. The key purpose total alkalinity serves is to help control the pH in the pool. It does this by acting as a buffer so that when materials are added to a pool that would otherwise cause the pH to go up or down, these changes are managed and do not result in severe changes to pool water balance.
What is Cyanuric Acid?
CYA is short for Cyanuric Acid–also called conditioner, or stabilizer. CYA is a chemical used to protect chlorine from direct sunlight. Direct sunlight can break down chlorine in a matter of hours. So without protection, chlorine does not last very long in outdoor pools. Since indoor pools do not have direct UV exposure from the sun, CYA stabilization is unnecessary.
What is the Langelier Saturation Index (LSI)?
A perfect score on the LSI is zero (0.0). Zero is perfectly balanced water; saturated with the perfect amount of calcium and dissolved solids, and has a stable pH. Being the universal solvent, if water is out of balance, it will naturally try to find its own balance and equilibrium, because it wants to be at 0.0 LSI. For instance, if there is not enough calcium, water will dissolve and extract it from the plaster walls of the pool (etching).
What is Calcium Hardness?
The sum of all the calcium dissolved in water is referred to as the calcium hardness. Calcium is important since high levels are unstable and become even more unstable if the pH or the total alkalinity rise above the normal levels. These imbalances can result in cloudy water and/or scale. In addition, calcium does not like warm water. As water temperature rises, calcium becomes more likely to precipitate out of solution. Calcium is actually more soluble in cold water, which is why scaling of heater equipment is so common.