Personally, I'd attach the edge at the desired elevation, mask it off with blue tape, then tile. I find it easier to tile to an installed frame rather than adding the frame around the tile. Once I screwed a false edge to the top, then tiled to it, then removed the false edge and replaced it with the permanent edging. Mongo

Hi. Thank you for the prompt replay. One leg of the "L" is 1/2" long and lays over the front face of the tile. The other leg of the "L" is 3/8" long with a 1/8" flap that acts like a lock to keep the "L" locked into the very narrow space above the pool wall behind the tile and the under side of the cement deck. The small 1/8" flap at one end of the "L" forms a water seal between the top side of the pool wall and the bottom side of the deck. Imagine an upside down "L" at the front face of the tile and the upper edge of the tile extending between the lower edge of the deck. It appears the tile, which is cemented to the pool wall helps hold the plastic against the lower side of the pool deck. Bill

We used bullnose. I really wanted to do custom pencil liner but when we got the quote from our tile place, it blew the budget completely. I thought I would hate it because it didn't match my inspiration backsplash, but honestly it looks complete and I rarely think about it these days. I think either works fine; just depends on your budget and your options.

I guess my question is really about what is the difference between <20$ edge trim vs 100$ edge trim (it seems the material is aluminum vs stainless steel)? What is the cons of using aluminum ones in bathroom?