After two failed attempts to repair a crack in the seam of my sand filter, I am turning to the pros! What I have is a plastic tank (150 lbs) sand filter with about a 3/8 split in the seam. I'v tried 2 part epoxy, and quick steel on both the inside and outside of the tank and both have failed within seconds of turning on the pump, both just peel (epoxy) and break (quick steel) off the plastic very easily like its not adhering to the plastic (yes i sanded it first). So... does any one have any idea of a way to fix this? I am leaning towards fiberglass, but not too sure if it will stick to the plastic ? what i really need is something that chemically bounds too the plastic, if such a products exists. Any help is greatly appreciated...