Preparation

• Drain the water from the pool. Extend the size of the crack by one inch on each end and a half-inch in depth using a saw with a diamond blade. Remove any loose concrete and debris from around and inside the crack with a brush and leave it to dry.
  
  

Repair

• Apply caulk inside the crack with a caulking gun and fill until a quarter-inch below the edge and leave it to dry. Mix the amount of commercially available plaster or pebble pool repair patch you need with bonding agent to a workable consistency. Push the prepared patch into the crack with a putty knife so it covers the quarter-inch space between the caulk and top surface. Press it lightly to remove trapped air bubbles.
  
  

Finishing Touches

• Smooth out the patched area with a trowel and tamp it with a moist sponge so it resembles the consistency of the surrounding surface. Refill the pool when the repair patch is completely dry.