If your chlorine levels are in the "what am I, a hospital?" zone—say, over 10 ppm—you need sodium thiosulfate. This is the chemical that pool stores sell as "chlorine neutralizer." It’s basically a chlorine eraser. A tiny capful can drop levels by several ppm instantly. It’s like a pool version of CTRL+Z for overzealous shocking.
But here’s the hilarious trap: too much sodium thiosulfate will drop your chlorine to zero. And then you’ll wonder why your pool starts looking like a swamp monster’s bathtub. So measure carefully—use a test kit, not your gut feeling. Your gut doesn’t know chemistry; it just wants nachos.
