The deck of a pool doesn’t directly butt up against the wall of the pool itself; a thin line of coping (concrete material) bridges the gap as insulation from water seepage. Filling in a crack between the deck and the coping is a straightforward, if somewhat time-consuming, procedure that must be done to protect the deck. You will need supplies and tools acquired from a hardware store or a home and garden supply shop. There is no need to empty the water in the pool, but keep the pool off limits until after you have finished making the repair.
Place a plastic tarp on the coping, an inch or so away from the gap between it and the deck. Tape the tarp to the coping with strips of duct tape.
Turn the pool pump off at the pool’s electrical panel -- typically located in a shed at one end of the pool. Trip the circuit breaker to disconnect all electricity from the pool -- the fuse box is typically at the same location as the panel. Put on old clothes, a face mask and protective eye gear and gloves.
Place the tip of the chisel into one side of the crack at a 45 degree angle. Strike the chisel with a mallet to gouge the inside of the crack. Move the chisel along the length of the crack, striking the chisel every inch or so. Lift the chisel out of the crack once you have reach its other end.
Remove loose debris from the crack and from around the crack with your fingers. Place the debris in a garbage bag for disposal later. Brush out the crack with a nylon brush. Remove the loose dust from inside the crack with the edge of water-moistened paper towels.
Pour the bags that come with the epoxy grout kit into a bucket. Add tap water as per the instructions that accompany the epoxy grout kit. Stir the mixture in the bucket with a wooden stir stick until there are no streaks in the mixture. Add the sand that comes with the epoxy grout kit to the mixture. Stir the mixture until it reaches a paste-like consistency.
Apply the mixture to an edge of the wooden stir stick. Place the edge of the stick against the coping, to one side of the crack. Press down on the edge as you drag the stick along the length of the crack, filling in the crack. Remove the stick once you have reached the other end of the crack. Reapply epoxy grout to the stick and repeat the procedure until the crack is completely filled.
Place the edge of a putty knife against the coping, to one side of the now-filled crack. Press down on the edge as you drag the putty knife along the length of the crack, leveling the top even with the rest of the coping. Lift the putty knife off once you reach the other end of the crack.
Let the epoxy grout set for the amount of time specified in the instructions. Remove the plastic tarp and restore power to the pool and to the pool pump.