Plaster is like Sandpaper

[Mikes Pool]

If there's no grit on the tile or plastics, you need to take a look underwater with a mask or goggles, and see if it's raised or depressed.

I looked at the plaster with goggles and the plaster is pitted but also rough like sandpaper. I took a 1" putty knife to a small area of plaster and I was able to make it smooth but obviously the pits are still there.

Tell me about the "bubbler" -- what is it, where is it, when does it run . . . and most important, did you maintain a normal (<7.8) pH while it ran?

The 2 bubblers are in the shallow tanning ledge and run all the time for the "bubbling brook" effect. The pH is in the high range most of the time.

I'm afraid I may know what happened; telling you my suspicions may help you confirm or deny them:
1. Your 'bubbler' -- presumably some sort of continuous aeration -- ran quite a bit.

Yes.

2. Because you were a conscientious pool owner, you maintained a proper pH . . . but you didn't check TA all that often.

Yes.

3. Because the pool industry -- except for my site and a couple of derivative sites -- does not understand how carbonate alkalinity works in pools, no one warned you what happens if you (a) aerate and (b) maintain the pH. This page -- http://pool9.net/alk-step/ -- explains what happens.

Yes.

4. You ended up running a pool with VERY low carbonate alkalinity, which eroded your plaster, even though the pH was normal.

I think the alkalinity readings were within range most of the time.

5. Consequently, you ended up, not with scale, but with corroded plaster.

It almost seems as though I have both since I am able to scrape the grit off. Is that possible? Chemically speaking.

An inspection from 6" away with goggles will tell. It will be easier if you do so early or late in the day, so the light striking the plaster at an angle, rather than from directly overhead.[/QUOTE]

I read the article at the link you posted about lowering alkalinity but it seems like my numbers are all within the satisfactory range so right now I'm sort of confused. I plugged my numbers into the saturation index and came up with +0.5. If the pool readings taken yesterday are correct and the saturation index is correct and taken with the article about lowering alkalinity, now I'm really confused!

So my questions are:
1.If my plaster is damaged, what can be done, if anything?
2.What do I need to do to get my pool in balance? Based on the SI.
3.Is there a way to remove the sandpaper feel chemically? The pool is too big to do with a 1" putty knife.

Again, thank you for your assistance.