I have a gunite pool that I fiberglassed with fiberglass fabric sandwiched between two coatings of epoxy (Pilgrim Permacoat, Inc PLASTIC product). It has held up great, really, for 11 years. Now it's starting to peel away from the top where I had a stone mason level the surface where the waterline tiles had fallen off. I think he just used mud...and it failed. Now I have to tear out all of the fiberglass and old tile (we ran the epoxy and glass right over the tile that was still there and it held perfectly). It's the areas where the original tiles had fallen off that were mudded and then failed. I want to install waterline tile. So I'll cut the epoxy/glass down below where the tiles will be and demo all of the old tiles and such.
My question is this. What product do I use to fill-in and level out the surface below where the tile will be? I am thinking there will be some big gouges and gaps and such that will need to be filled in prior to applying the thinset and tiles. And, is there a recommended thinset for pools?