If you have a bathtub with a slip-resistant bottom that still looks dingy, grungy and downright grimy no matter what you use to clean it, I have really good news and at least one surefire solution that will even bring an older tub bottom back to being clean and like new!

Since the Americans with Disabilities Act became law in 1990, all bathroom flooring must be non-slip. Kohler porcelain tubs come with a patented Safeguard slip-resistant surface, which has a very distinctive look and seems to be the most prone to this ugly, dirty problem.

The problem is not only with Kohler tubs but any manufacturer that etches the bottom of the tub to provide the non-slip feature. Oil from your feet starts staining the bottom, and it's like these stains get embedded and locked in forever.

I've heard from many readers who have tried everything they can think of to remove these stains and not had success. In fact, all of those efforts seem to do just the opposite: permanently lock in the stains and make the problem even worse.

Some readers have reported using a Magic Eraser, a Bar Keepers Friend, Zud and Comet with sketchy and somewhat limited success. But Kohler warns against all of them because they can harm the finish, possibly creating an even worse problem over time.

Kohler recommends only three products to clean its Safeguard slip-resistant surface: Clorox Disinfecting Bathroom Cleaner, Tilex Bathroom Cleaner and Express ROG3 Tub and Tile Cleaner.

ROG3 Tub and Tile Cleaner is the surefire product I mentioned above. I can verify that it is miraculous and will bring your tub and the slip-resistant etching back to being shiny and new without damaging the porcelain or the anti-slip surface. You can get this product from the manufacturer website. Actually, it comes in a kit. In the kit, you will receive two bottles, ROG3 and ROG1, plus a scrubbing pad. It costs about $40 plus shipping, which is quite a bargain compared to having a tub refinished or replaced.

The kit will come with full instructions, which are quite simple. I suggest that you take a few minutes to watch this online video that will show you exactly how to use the product: https://youtu.be/xBogUwxfNTo. Then, read the information on the ROG3 site.

While ROG3 Tub and Tile Cleaner is a Kohler-recommended product to clean the slip-resistant bottom of a bathtub, it is not limited to that. This product will rid all tubs, showers, tile and grout of dirt, grime and buildup that need a miracle.

Mary invites questions, comments and tips at [email protected], or c/o Everyday Cheapskate, 12340 Seal Beach Blvd., Suite B-416, Seal Beach, CA 90740. This column will answer questions of general interest, but letters cannot be answered individually. Mary Hunt is the founder of www.DebtProofLiving.com, a personal finance member website and the author of "Debt-Proof Living," released in 2014. To find out more about Mary and read her past columns, please visit the Creators Syndicate webpage at www.creators.com.