I have a crack in the pool wall that is about six inches long from the top of the tile. The crack is less than 1/8 inch thick. I have used pool putyy to repair it several times but eventually kit opens again. What is the best way to prevent a crack from moving back open? I saw a product, don't remember the name, in which you drill a hole on each sice of the crack, place a bar and tighten the bollts to a certain torque. Any ideas.