What can I use to remove yellow hard water stains from the bathtub?

You can try blue dawn and vinegar

Thank you Janet. I will.

if that doesn't work try baking soda and vinegar into a paste similar to cleanser and scrub the tub with it. also mr clean magic eraser works too

CLR - it's a cleaner that is used to remove calcium, lime and rust stains. Works great on tubs and sinks.

Baking soda, vinegar, and lots of elbow grease :)

Thank you June.

I tried baking soda, vinegar, scrubbing, blue dawn, bleach, bar keepers scrub, etc. and it yellow is still there. Do you have any other suggestions pleas?

Is this a cast-iron or an acrylic bathtub?

baking soda and vinegar worked best with me

I painted my tub and walls with an acrylic latex paint.

Acrylic bathtub.

bakingsoda scrub

Try hot water and dishwasher detergent. Let sit overnight.