Everything you put in the pool. Chlorine tablets, shock treatments, algaecides—they all add solids. Even if you use the crystal-clear tablets of a magical unicorn, they still leave behind a dissolved salt residue. It’s like the universe hates clear water.
Then there’s you. Bathers are TDS factories. Every splash of sunscreen, every dab of lotion, every flake of skin—thank you for your contributions, they all add up. Next time a kid pees in the pool, just remember you’re not just getting urine; you’re getting a TDS bump. You’re welcome.
Rainwater can actually lower TDS (because it’s pure-ish), but if you live near the ocean, you get salts blown in. And if you have a cover, evaporation concentrates dissolved solids—your pool shrinks but the crud stays. It’s like concentrating a broth.
