One method to try: spread baking soda paste over the floor, then pour vinegar over the surface. Wait for the baking soda and vinegar to react - they will fizz. This should help loosen the debris, so it is easy to scrub off. If you'd like to get input directly from a plumber you can chat directly or schedule a video chat with a pro (for free) at https://hellodwelling.com
What is your shower floor made of?
If fiberglass, like mine, I use a mixture of blue dawn dish soap and white vinegar.
Take a 32 oz water bottle (empty) and add 5-6 oz blue dawn dish soap, fill with the vinegar. Replace the cap and give it a mix. Put a few slits or holes in the cap and spray it into the shower, let it set a few minutes. Take a new Dollar store broom (blue bristles and a white handle) and clean the shower. Rinse both the broom and the shower. The broom will remain dedicated for this task, because you do not want anything in it to scratch your fiberglass.
There may be a build-up of calcium on it. Maybe a good cleaning with Lime Away will help!
You could use an Acid Floor Cleaner for Tile, Brick & Concrete! If that is not something you want to use, Have you tried Toilet Cleaner that removes Calcium! If that is also not something you want to try, have you used Barkeepers Friend. If that doesn't work for you maybe Gunk remover or re-tile over . Best wishes.
There is some good information here:
It does kind of depend on what your floor is made of but for the absolute worst impossible jobs I always end up grabbing a bottle of The Works Toilet Bowl Cleaner. It really does work!
here is some more info for you
Hello Edie, hope this helps you out
Easy Off No Fume Oven Cleaner in the BLUE can. Works on enamel, porcelain, and fiberglass
Fill a spray bottle with a 50/50 solution of Dawn dish soap and vinegar. Spray it on the shower floor and let it work. If they are tough stains, you may have to scrub with a plastic scrubber! Rinse it well - it will make the floor slippery.
Hello what is your shower floor made of is it fiberglass or tile. More information might help get the most appropriate solution for your problem.
To clean a really filthy, scummy and stained fiberglass tub, shower etc, you simply need to make sure the fiberglass is dry, then spray a can of oven cleaner over it all. It may take more than 1 can, depending on size of shower or tub. It will also work to clean soap scummy glass doors too. Then turn on the exhaust fan and close the bathroom door and put a sign on the door to keep everyone out for a couple hours or so. When you go back in there, open the window and leave fan on. WEAR RUBBER GLOVES. Take a green scrubby pad, and scrub down all the fiberglass surfaces, starting with the bottom surfaces and working your way up, rinsing as you go. You could use a scrub brush instead, but the green scrubby pad is the most effective tool to get absolutely everything off, without missing areas. Use the same method for the glass clean-up. Mind you, this is the only solution I've found that works when your traditional bathroom cleaners are not strong enough to do the job. And after the whole thing is cleaned up and amazing looking, you should never have to do it again, as long as you do a weekly cleaning of all the fiberglass in the bathroom, using conventional bathroom cleaners, or baking soda paste etc.
Just be sure to use Easy Off in the blue can.