i recently got a new big bath tub. i've only used it maybe 5 times. unforchantly, their are a few black marks going across the tub. like someone took a black pen and made some ink dots and lines. ( i have no young children to blame) it isn't mold. and it's impossible to clean. i've scrubbed with every cleaner that i have. i cant even scrape a little off with my finger nail. its stuck on the tub! i'm guessing it's just really stubborn dirt or something. its aggravating.

any suggestions?

any help? pretty please? come on guys!

Have you tried a Magic Erasure? You didn't say what type of tub it was? Porcelain, fiberglass? Usually the erasure and a bleach cleaner like clorox cleanup would take it off. Don't like bleach try vinegar and baking soda.

it's got to be some type of dirt or mold problem. not to gross you out, but that's what it's got to be. try using a good brand of multi-purpose bathroom cleaner and let the SIT there for a good 7-10 min. then start your scrubbing and cleaning again. i'm sure it'll come right off.

I would try a cleaner made for porcelain. Zap works pretty well for a lot of porcelain stains. Usually the problem stains for porcelain are rust stains which is a mineral build-up. Lime-away and other acidic cleaners work well for this. But a black mark may be something entirely different. Are you sure it's not really dark green? Something else you could try is a pumice stick. They sell them at janitorial stores - they are mainly used to clean the bowls of porcelain toilets.

Kitsap Window & Gutter Cleaning

I ended up getting it off. It was some tough dirt...Just used some regular bathroom cleaner- i let it sit in for a while and scrubbed away as hard as my heart's desire. looking brand new thanks guys

Glad you got it off of there! Out of curiousity, what type of tub is it? Fiberglass or cast iron?

Have you tried using a bleach and water solution with some type of scrub brush or SOS pad?

Lemons can also help with rings and marks just by rubbing them directly onto the areas...hope this helps you in some way!!

glad you figured it out

To those who asked- it's a fiberglass

These does not sense like embedded marks as you explained. Is it like paint may be .
May be you should paint over them on your bath tub like we do on car scrathes with scratch remover pen.

That's awful. What kind of cleaner did you use to get rid of that?!