How to Clean a Bathtub with Bleach
To wash a bath tub with bleach, start by rinsing the tub with hot water to loosen the grime. Next, combine 1/2 a cup of bleach with 1 gallon of water in a container. Then, dip a sponge into the solution and wipe the surface of the tub. After 5 minutes, rinse it off with a sponge and cool water. If you still notice grimy patches, make a paste of equal parts baking soda and bleach, apply it to the affected area, and wash it off after 15 minutes.
Remove everything from the tub. If you have any loofahs, soaps, or bottles of shampoo, conditioner, or body lotion, take them out of the tub. Place them on the counter or somewhere out of the way where they will be safe while you clean the bathtub with bleach. Rinse the tub out. Turn the hot water on briefly and run a sponge under it. Turn the water off. Use the damp sponge to wipe down the surface of the bathtub. This will help loosen grime and material, making it easier to eradicate tub scum later with bleach. Mix bleach with water. Combine ½ cup (118 milliliters) bleach with 1 gallon (3.8 liters) of water. Dip a sponge into the solution and wipe it across the surface of the tub. Wait at least 5 minutes before moving on to the next step. Rinse the tub again. After you've left the bleach solution on the tub for at least 5 minutes, dip another sponge in cool water and wipe the tub with it by moving your hand in a gentle circular motion. Wipe the tub dry using a towel. Make a baking soda paste to scrub away tough stains. If your bathtub is still grimy, mix a paste of equal parts baking soda and bleach. Apply the paste to the grimy or discolored area. Wait at least 15 minutes, then spray water on the paste and use a damp sponge to wipe the paste away, moving your hand in a gentle circular motion. Dry the area with a towel. Check your tub’s user manual. Some manufacturers recommend closing the air controls during cleaning. Others recommend leaving them open. And some manufacturers prescribe (and proscribe) the use of particular cleaning products. Consult your manual to discern the best way to proceed. Fill the tub. Turn the water on. As the tub fills, add ½ cup (118 milliliters) of mild dish soap and 4 cups (1 liter) of bleach if your tub is really gross. If your tub only needs a mild cleaning, add just 2 cups (1/2 liter) of bleach. If the water from your tub's faucet does not reach at least 140° Fahrenheit (60° Celsius), you'll need to boil some water on the stovetop until it reaches the appropriate temperature, then transfer it to the tub. Run the jets. Turn the jets on for 20 minutes. At the end of the 20 minutes, empty the tub by pulling the drain out of the bottom. Fill the tub again. Turn the water on. This time, though, you need only fill it with lukewarm water (even cool water should work just fine). Don't add soap or bleach. Turn the jets on for another 20 minutes. Drain the tub. By this time, all bleach residue should be thoroughly drained. Just to be sure, though, wipe the inside of the tub down with a towel. This will prevent skin irritation should any bleach residue remain. Ensure bleach is safe to use on your tub. Do not use bleach on tubs containing iron. The bleach will cause the iron to oxidize, leaving behind red streaks. Using bleach on acrylic or enameled bathtubs is also generally impossible, as the bleach will cause the acrylic coating to decay. Some manufacturers of acrylic tubs do permit the use of powdered oxygen bleach. Consult the owner's manual for your tub or contact the manufacturer for information about whether such a product is acceptable for cleaning your tub. Open the window. The stench of bleach can be overpowering and cause breathing problems if used in high concentrations. Keep the door to the bathroom open, too, and turn on a fan if necessary. Do not mix bleach with other cleaning products. Mixing bleach with ammonia or vinegar, for instance, can cause toxic fumes. Mixing can happen on the bathtub's surface, too, so wipe or wash away one cleaning product before applying another. The only thing you can safely mix with bleach is water. Protect your skin and eyes. Bleach is rough on skin. To protect yourself, wear heavy-duty rubber cleaning gloves.  Additionally, wear eye protection like safety goggles or glasses. Wear old clothes. Bleach discolors fabrics. If you accidentally splash bleach on your clothes, you'll end up with white stains where the bleach comes in contact with your clothing. To prevent ruining your favorite outfit, only wear clothes you don't particularly care for when using bleach to clean your bathtub. When patting down the inside of your bathtub, use a white towel, or one you don't mind getting discolored. Use baking soda and vinegar as a bleach alternative. If you want a gentler and more environmentally friendly alternative to bleach, try gently scrubbing your tub with a little baking soda and a scrub brush or washrag. Mix up a solution of 4 cups (0.9 liters) of hot water and 1 cup (0.2 liters) of vinegar, then dip your brush or rag in that and go over the tub again, giving special attention to stubborn areas. Rinse the tub as you would after using bleach. 
Remove everything from the tub. Rinse the tub out. Mix bleach with water. Rinse the tub again. Make a baking soda paste to scrub away tough stains. Check your tub’s user manual. Fill the tub. Run the jets. Fill the tub again. Drain the tub. Ensure bleach is safe to use on your tub. Open the window. Do not mix bleach with other cleaning products. Protect your skin and eyes. Wear old clothes. Use baking soda and vinegar as a bleach alternative. 