Anyone know of a home remedy to get rid of a stain around the bathtub ?

baking soda

Take a plate full of baking soda and a lemon cut in half. Dip the cut side of the lemon into the soda and use it like you would a scrubber. It gets off grease and soap scum, and smells awesome. No harsh chemicals, and rarely allergenic. I also use it to clean the microwave, then soak in a glass of hot water overnight and drop into the garbage disposer in the kitchen sink. The left over baking soda from the bathtub also helps scrub the disposer till it shines as you run it!

Try this: Put 1/4 cup powdered dishwasher detergent in a glass measuring cup, and add just enough water to make a paste; stir with a nonmetal utensil (I use a plastic chopstick), then apply to the stain, scrub lightly, and let set for 20 minutes. Rinse well. Unfortunately, you may not be able to remove the stain if the glaze on the tub has worn off.

You can use fine sandpaper to remove stubborn stains from old porcelain fixtures. Plumbers do it all the time when they accidentally leave marks with tools, etc...

I didn't believe it when my brother (professional plumber) told me that... But, there are some very old fixtures in the apartment I'm living in and I removed some stains I couldn't have removed any other way with some sandpaper. No apparent damage... The areas I sanded are not becoming stained again either.

Really. None of these is doing it for me either. I've used dish soap and a SYNTHETIC, not natural pumice-type pad or block used for feet, on my tub rings. They're gone byebye. My tub is NOT porcelain, it is acrylic, and there's no way I'd try half of the stuff people here have advised, since I can't afford to ruin it and have to afford a replacement!!

A Mr. Clean magic eraser

Bleach and water in a spray bottle. Spray on surface and watch stains crawl off. Then rinse off with shower head.

make a paste of baking soda and lemon juice

rub into the area you want to clean, let sit about 20 minutes then go wash it off

here's an old witches remedy (not really) take a raw chicken, and rub it around the stain. bury the chicken when the moon is full, as the chicken decays, the stain will go away

Try mixing baking soda and vinegar with a large helping of elbow grease.

a good suggestion is to immediately clean the tub after you take a bath.