How to Clean your Bathtub with a Grapefruit and Salt  Materials 1 Grapefruit ¼ cup kosher salt Instructions Halve Grapefruit: 1 medium to large grapefruit will clean your entire bath or shower from top to bottom, including all the fixtures.  Simply cut the grapefruit in half. Sprinkle with Salt: Using 1 grapefruit half at... Continue Reading →