How do I remove pool tile scale without damaging the tile?

Use a wet pumice stone dipped in white vinegar to gently rub the scale. The vinegar softens the calcium, and the stone buffs it off without scratching. Avoid wire brushes, steel wool, or muriatic acid, which can damage tile and grout. For thick scale, let a vinegar-soaked cloth sit on it for 15 minutes before scrubbing.