I purchased several of these tubs less then 5years ago, and now they have standing water depression in the tub with causes discolor in that area.
It was recommened that I dont use any cement under the tub, and would have voided the warrenty. I am a master plumber and would recommend not to buy this type of tub. I am going to try to get my money back and have remoldel the tub area of my bathroom again.