Pool cracked in the corner and I chiseled it out to let the water drain. Pool builder is not an option. I want to seal this crack, if possible, with hydraulic mortar mix, I then want to fill that corner with concrete, and build out and extend the stone down from the water fall to the bottom of the pool. What type mortar and concrete should I use for this? Also, is necessary to tie the new concrete into the existing pool wall with rebar? I can do this. I just need to know if I am on the right track.