To replace these, the pool must be empty of water. Temporary repairs may be possible, by securing the return fixture with underwater epoxy resin.
Here are the steps for replacing a wall or floor return in a gunite pool.
1. After the pool is drained of water, saw cut 12 inches of plaster on all sides of the return, so that the return is centered in a one-foot square.
2. Chip away the pool plaster and remove the gunite or concrete that surrounds the return, using a chisel and hammer. An air-compressed chipping gun may also be useful. This will expose the entire fitting and pipe.
3. Remove the cover plate from the return.
4. Using an electric drill and inside-pipe cutter, cut the fitting out, following the manufacturers instructions.
5. Create an elevation for the new return that meets local and state codes. Measure the new fitting, to be sure that the height is correct.
6. Using the proper schedule-40 or schedule-80 fittings, glue the new fitting in place, with the proper gluing technique (cleaner, primer, glue).
7. Apply hydraulic cement to secure the fitting, making certain to leave space for final plaster repair.
8. Complete the plaster patch, making sure all edges of the fitting are flush with the patch.