At the very bottom, faded nearly to white, were the last two rules: Never mix chemicals. Ever. Trichlor + Cal Hypo = fireball in your face. Add acid to water, never water to acid. Mark looked up from the sheet. His pool was no longer green. It was a milky, confused blue—the color of dawn after a bad night. He set the filter to run overnight. He put the cheat sheet back in his own bucket.
The next morning, the water was glass. And somewhere, Old Man Henley smiled. pool chemical cheat sheet
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. At the very bottom, faded nearly to white,
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. Add acid to water, never water to acid
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.