My wife and I recently bought our first house and it came with a pool. We found that the FC level was hard to keep up due to very high CYA (who knows how long the water had been in the pool before we bought it--but the house wasn't kept in great shape, so the pool was probably even more abused). We ended up draining the water, and were debating having the pool re-plastered (there is lots of metal staining, etc), but due to the cost, we decided to wait, and refill with freshwater instead. I just got the water chemistry where I wanted it this past weekend, with a huge thanks to these forums!
My issue is that upon getting into the water to inspect stuff (and enjoy my pool for the first time), I found a few instances of spalling--a few square inches here and there. I'm fairly sure this is at least in part due to the pool being empty for a week (I know you're not supposed to do that but we wanted a few bids for the re-plaster work and we live up on a hill so we didn't think the water table pushing up would be an issue). We also just started using our automatic vacuum this weekend, and I've read that plaster that has begun to spall (is that a verb?) is often revealed when the suction of a vacuum moves over it.
My questions are:
(1) Is this spalling anything other than an unsightly nuisance, or should I be concerned for the structure of the pool?
(2) If I went underwater and pushed against the plaster and nothing flaked off, can I assume nothing will flake off within the next year--that is to say, will whatever flakes off now be the extent of the spalling?
(3) Are there any caveats to water chemistry I should keep in mind to slow the spread of this spalling, or is it purely based on the inferiority of the plaster?
(4) I've read that spot sanding will help smooth out areas like this.. what grit is recommended? Do I need a special time of sandpaper to sand underwater?
Keep in mind, we plan to re-plaster next year, so I just need everything to hold until then. I can deal with it being a little unsightly for a bit.
Thanks in advance!