I recently purchased an American standard bathtub. Americast finsih I believe. Basic white, 60x30 inch tub. We have the same material in our kithchen sink and it works great. After unpacking it I noticed all the literature in the box on cleaning, specifically with the Stan-sure non slip surface. I did not realize the tub had grit embedded on the bottom and am concerned that this will be a pain for continuously cleaning, and worse, wear off leaving a damaged surface. We have hard water. Our my concerns justified? would I be better off returning the tub and getting another make.