it's a good idea to seal it with a polyurethane sealant. Sealant keeps mold and mildew out of the grout and prevents discoloration. This would be a perfect time to clean the grout on the rest of the floor and give it arefresher coat of sealantas well....
A standard bathtub mat usually comes with a general contour cut to fit around the drain of most bathtubs. The soft rubber mats should preferably be made of mold-resistant latex-free rubber with the underside covered with a multitude of suction cups to make it adhere to the bathtub floor. ...