How can I bring the bottom of my bathtub back to not having the dark s

Baking soda mixed with vinegar into a paste. Leave on 15 minutes, then rinse.

You could try bleach

Try using some calgon water softener, sprinkle it on a wet bottom and scrub with one of those green scrubbies. You can leave it in placve if it is working and add just a tiny bit of dish detergent and scrub again and rinse, The Calgon water sofener on your cleaning cloth to wash the tub works great on any bathtub rings too. Also glass shower doors come sparkly clean as the Calgon removes soap film better than anything else I have ever used. I found that lemo0n oil thing just turned the soap film clear for a lttle while but didn't remove it. Calgon will remove soap film from your fixtures too, just be sure to rinse well, especially the bathtub which will be slippery, squeaky clean.

Easy Off No Fume Oven Cleaner in the BLUE can. Spray it on and let it liquefy. May need some scrubbing. Wear rubber gloves. Rinse well. Works on enamel, porcelain, and fiberglass.

I had the same problem. Magic Eraser and elbow grease and determination.

Wow thanks so much, I will buy one tomorrow

A lot of tubs and showers have a non slip surface. Hard to clean conventionally with the texture. Oven cleaner does clean the grime. You can try in a small area and see what happens.

Use shout Liquid stain remover. Mix with baking soda. Let it sit for a few hours, lightly scrub. Should do the trick.

The finish is already ruined. I made the picture larger to take a good look . You can still see some shiny spots of porcelain at the bottom.

Bleach and comet are really bad to use on porcelain it will eat the finish

Hi Willa, this video tutorial should help - https://www.youtube.com/watch?v=Z5DeFMz9Pc0