I am a new gunite pool start up. The pool was plastered 5/5 (Quartz Finish). I have a bench and one of the returns is only about an 1 1/2 off the top of the bench where you would sit. I always thought that was wrong. Anyway, last night I noticed some discoloration on the bench right by the return. It turns out the force of the water is eating away the plaster. It is much rougher and pitted than the other areas which are quite smooth. I immediately pointed the return higher so it is rippling the surface water. The return was not directly hitting the bench, but the residual force was enough to do damage. Any suggestions on how to smooth of the area which is about the size of a baseball?