Pool Chemistry in Plain English
pH, alkalinity, cyanuric acid — what each number actually means, and why getting them right matters more than the brand of chlorine you buy.
Most pool chemistry problems come from a single misunderstanding: pH and chlorine are not independent. They depend on each other, and on a handful of supporting numbers that rarely get attention until something goes wrong.
Total alkalinity is the buffer that keeps pH stable. Aim for 80–120 ppm. Too low, and pH swings wildly with every rainstorm. Too high, and pH gets stubborn — it resists every adjustment you make.
Cyanuric acid (CYA) is sunscreen for your chlorine. In outdoor pools, 30–50 ppm protects chlorine from being burned off by UV. But push past 80 ppm and chlorine becomes sluggish — you'll need more of it to do the same work.
Calcium hardness rounds out the picture. Below 150 ppm, the water gets aggressive and starts pulling calcium out of your plaster. Above 400 ppm, you'll see scale on tile and heater elements.
Get these four numbers right and your pool basically takes care of itself. Get them wrong and no amount of chlorine will save you. Hitting them every week is the core of our pool maintenance service, which covers Friendswood and the surrounding Bay Area.