I bought an 15' x 48" intex metal frame pool, near the end of the season, one side of the pool started sinking through the tarp and into the ground. I want to prevent this from happening next season when I put it up. I have prepped the ground for where I'm going to place it next season. I was just wondering if anyone who has this type of pool have any useful tips for me to prevent the sinking? I also plan on purchasing the Rhino floor pad, should I purchase the same size as my pool 15' diameter or should I go 18' diameter?