Thanks for the replies. I don't even know the extent of the roughness and won't know until I can get in. I'm hoping it's fairly limited and manageable. The plaster (just smooth white plaster) was very smooth when it was done last fall so finding these rough areas was pretty upsetting to say the least. I don't have the discoloration that Guido described.

It's hard to believe that this could happen in such a short time. I closed the pool in early December and prior to closing I lowered the water about 15". Some of the roughness I am feeling is on top of the step into the spa, which was easily out of the water when I put the cover on. We got a lot of rain over the river and the pool ended up a little above the normal fill level, but that top step would have been dry for a while. So the damage to that step would have happened is just 2 or 3 months! It seems hard to believe. Yeah, the PH and hardness were out of whack but it's hard to believe that could have an effect like this in such a short time.

Also, the roughness is mainly on the top of the steps and the top of the spa bench. The sides still feel fairly smooth. I'm really hoping that a good stiff brush might take care of this. I'll check back in a week or so after I've tried that.