I installed new return jets in a fiberglass pool that has been tiled. We placed the return jets on top of the tile with a gasket and silicon around the borders of the jet face plate. The jet face plate has threads that screw into the fitting in the back, sandwiching the gasket and the tile. We have some leaking and I am not sure if it is the threads. Has anyone installed return jets over tile, what would be the solution to fixing this problem, Silicon on the inside of the threads?