Pool Chemical Cheat Sheet May 2026

The day the water turned emerald green was the day Mark realized he’d been treating his pool like a bathtub. He’d been lucky for two summers—dump in a little chlorine, run the filter, swim. But this year, the algae laughed at him. It wasn't just green; it was thick , a viscous bloom that looked like someone had liquefied a golf course.

His neighbor, Old Man Henley, who had a pool so clear it seemed to exist in a different dimension, walked over with a plastic bucket. Inside: a tattered, laminated card. "Pool Chemical Cheat Sheet," it read. But it wasn't a list of dos and don'ts. It was a story. pool chemical cheat sheet

The middle of the sheet was a cautionary tale. Cyanuric Acid (CYA): Sunscreen for chlorine. 30–50 ppm. Above 100 ppm? You've built a prison. Chlorine can't escape, but it can't work either. Only draining the pool sets it free. Mark tested his CYA. 180 ppm. He had been using stabilized chlorine tablets for three years. Each tablet added a little chlorine and a lot of CYA. He was slowly poisoning his pool's immunity. The sheet’s solution was brutal: Partial drain. No shortcuts. The day the water turned emerald green was

And then, a note on calcium: Calcium Hardness (200–400 ppm): Too low, and the water eats your plaster like a sugar cube. Too high, and it rains scale—white flakes of regret on your tile line. It wasn't just green; it was thick ,