Things You'll Need
Piece of heavy cardboard
Acrylic bathtubs do not weigh very much, unlike bathtubs that are made of other materials, making anchoring them properly a very important step in the installation process. You must make sure the bathtub is level before you anchor it, or problems with the proper operation of the bathtub's drain will result. Not properly anchoring the bathtub to the surrounding walls can also lead to the bathtub cracking, creating extra work as you try to either patch the cracks or remove the bathtub and install a new one.
Place a level on the bathtub to make sure it sits level in place. If the bathtub is not level, remove it and tack shims to the legs where needed, then replace the tub.
Look for gaps between the flange or upper lip of the bathtub and the wall studs. Place shims in the gaps to prevent damaging the bathtub's upper lip when you anchor the bathtub to the walls.
Place a piece of heavy cardboard over the top lip of the bathtub. Drive roofing nails through the metal mounting brackets that sit above the edge of the tub, securing them to the studs in the wall.