scrub down the inside of the tank with a long-handled brush. (Be sure to wear gloves.) Use a smaller brush or an old toothbrush to clean any slime or discoloration from the fill or flush valves.

Wait 10 minutes, scrub the inside of the tank with the toilet brush, and let it sit for 20 minutes before flushing the tank clean. There's no need to rely on commercial toilet bowl cleaners.