Guys, one of the tiles that was in place right below my hot tub overspill has fallen off either during the winter or since my opening yesterday. I fished it out and noticed a little of the plaster that was below of it came off it. I think the water spilling from the tub edged a little space behind it as it falls and after a number of years it came lose. I see the little space behind the next tile also so that one will eventually fall off as well. My question is how can I glue this thing back. Can I do this with water level covering the entire tile? After couple more backwashes there will probable be about an inch of clearance on these tiles but I do not keep water any lower then that. Can I glue it with water level this high on the tiles? Secondly what about the plaster? do I need to replace that as well? is this something I can do or should get the professionals to take care of it?