Did you know that between designing fabrics, raising kids and making dinners, I also re-caulk showers?
Oh well, you gotta do what you gotta do!
Simple mix of water+bleach, 1:1 proportion.Scrub with this, and for especially dark grout lines, make paper towel strips soaked in the same mix, and leave them on top of stains for 10-15 min. Once you cleaned all the gunk, remove loose caulking and re-apply new. Let set, no water for 24 hours.
HINT: Clear caulk is so much more forgiving than white. Even if you mess up, it won't be so visible!
I also used masking tape to make the caulk go on straight and even. Just like you would with paint. Just make sure you remove the tape right away before caulk attaches to it.