I've read several threads about using vinegar-based solutions to keep mildew at bay. That's great once the mildew is gone, but what if you haven't kept on top of cleaning the shower and you have serious mildew buildup? I know something like X-14 would clean it, but that has horrible fumes. What else can I use? I don't expect magic (spray on and the mildew just disappears); I know I will have to scrub.