That's just nasty. Something had to be done. I scoured Pinterest to do some "research"
I found two different pins and compiled them to create what I am calling the miracle cleaner!
I poured bleach into a foil roasting pan and added lots of baking soda to form almost a paste. I got some of the long cotton strands from the girl that does my hair. It's the stuff they use when doing perms. They sell it at beauty supply stores, but she said I could just have some! Love having good friends! Anyway, I soaked the cotton in the bleach/baking soda mixture and applied it to the caulking around the base of the tub. Then I used an old toothbrush to apply the paste to the grout. I barely even had to scrub, and I saw results immediately! I left the paste on the grout for about ten minutes and then wiped it off with an old rag (one that I didn't mind ruining with bleach). The cotton I left longer so it could really get in there and kill that mold.
Here's a "during" shot.
Looks better already! We left the soaked cotton on the caulk for about 8 hours, but you could do overnight. When my husband and I took it off, we literally gave each other a high five. Holy smokes. The results were astonishing!
It looks like new! And we didn't even have to scrub it! Any time my house basically cleans itself is a win in my book!!