I patched a few rough areas in the shallow end with simple concrete patch. I vacuumed the heck out of it after I was done, but still ended up with a few sharp pcs here and there. The installer said not to worry since you can't feel them with your feet, but I can feel them when feeling around with fingers. We did all the prep work, bought the liner and hired the installer. The liner was $1100 and the installer charged us $1000 which included new main drain cover, return rings and skimmer plate (oh and another $50 for a light ring in better shape than ours was). The prep work involved removing the old vinyl liner (gross), cleaning up all the algae that accumulated over several months (gross), knocking off the rough spots on the side walls and priming those areas and some light concrete patch work. We are in a pretty wet area, so I had to keep a sump pump in the hopper for months, draining the water every few days. At wettest, we'd accumulate 4-5 of water over just a few days (just leaks thru the concrete)!