How do you remove a ring around the tub in an acrylic tub?

https://cleaning.tips.net/T005618_Getting_Rid_of_Bathtub_Rings.html

It sounds like the tub is older and dirt and chemicals from soap have permeated it. Try a Magic Eraser and also a cleaner that has Oxi-clean in it.

what color is the ring. Are there scratches on it? Is it a trick of the lighting...is there mold in the scratches...

I tried oven cleaner. Did not take it out completely but did lighten it.

Becareful on using alot of chemicals on this type of tub. You can destroy the protective coating most of them have. You could try a light mix of Vingear and water sitting on about 5-8 minutes. Otherwise I would call the manufacturer on the tub if known to ask them what they'd do about it. Maybe it might be as easy as just getting it recoated.

I hope your daughter the best on this.

Try magic eraser then seal with car paste wax

I would say someone has repeatedly cleaned this water line and damaged the finish, and it might be mold if it reappears after showering again. I would get some mold remover and clean it. Then I would get some acrylic tub sealer.... read the portion on sealents once you've cleaned it again... https://www.deltafaucet.com/design-innovation/inspiredliving/how-to-clean-acrylic-shower

Then maintain with.... https://www.walmart.com/ip/Gel-Gloss-GG166-Fiberglass-Polish-Protector-Bottle-16-oz/100775275?wmlspartner=wlpa&selectedSellerId=3706&adid=22222222227074366633&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=186789088726&wl4=aud-310687322322:pla-293000127555&wl5=9033057&wl6=&wl7=&wl8=&wl9=pla&wl10=113500026&wl11=online&wl12=100775275&wl13=&veh=sem

You might try toilet bowl cleaner and soft brush. Follow with vinegar diluted.

Scrubbing bubbles, works great.

Spray the scrubbing bubbles onto the ring heavily and leave it sit on there for a good while. Then whip it down with a sponge. If it's still there repeat it should clean it up.