A pumice stone works for most pool tile stains

Yes, but only on ceramic or porcelain tile — not on glass, metal, or painted surfaces.

A pumice stone is cheap, lasts forever, and chews through calcium scale and hard water stains without scratching glazed tile. Wet the stone and the tile, then scrub gently. That’s usually all you need.

For organic buildup (algae, scum), use a dedicated pool tile cleaner with bleach or a stiff nylon brush. If you still have stubborn scale, try diluted white vinegar or a citric acid cleaner — but test on a hidden spot first. Muriatic acid works, but it’s nasty stuff and easy to mess up.

Start with the least aggressive method and work your way up. Pool tile is tough, but it’s not indestructible.