I just bought a house with a pool. THe house is 30 years old and the pool is probably as old as the house. We had a home inspector and he didn't mention that there was any issues with the pool however there is some discoloration on the bottom surface of the pool, it is all over the bottom of the pool. Generally it just looks like a whiter shade of plaster or something. I noticed a couple of bumps in the pool but mostly it feels smooth (except those two bumps I mentioned). Do i need an acid wash or replaster or what? Wha are signs that a pool needs to be replastered, acid washed?