[Baldicon]

Thanks to all who replied. Looks like the tank is right below the sofa, so actually may not need to pull the coroplast. But I will file this info away for future reference. Now if I only knew how thick the flooring is. My sofa has not moved either, but I haven't had to make a full blown panic stop. I want to raise the sofa up by placing it on 2x4 laid flat on each end (and one maybe in the middle) so afraid in doing that it would be more apt to slide.