Quote Originally Posted by Mikes Pool View Post
It almost seems as though I have both since I am able to scrape the grit off. Is that possible?
Unfortunately, yes. When you erode the surface of the plaster, what's left is much weaker and even friable.

The alk-step article explains what has ALREADY happened to your pool, in an extreme and uncontrolled degree. I was NOT telling you what you need to do!

I first ran into this problem, years ago on pools with UV ozonation and venturi injection of a little ozone and a lot of air. What happens is the aeration from the venturi strips all the carbonic acid (a component of carbonate alkalinity) and thus drives the pH up. If you neglect your pool, and allow the pH to remain high . . . there's no damage. But if you are conscientious, and adjust the pH, you consume remaining carbonate alkalinity by converting it to new carbonic acid. And then the process repeats.

I'm sure, with the popularity of infinity edges, waterfalls, and yes, bubblers . . . this is a very common problem. It's approaching 20 years since I first published an explanation of this. 10,000's of pool users have PROVED that I was correct, and Chem_Geek has published an extremely comprehensive spreadsheet that displays the whole cycle in excruciatingly comprehensive and detailed fashion. But because the pool industry as a whole has never been willing to acknowledge the fundamental errors in the way they've dealt with carbonate alkalinity, the problem continues, victimizing both pool owners and pool builders, who've been mis-instructed.

Unfortunately, the only fix for having REMOVED the top layer of your plaster is to replace it, with either a replaster job, or by refinishing with epoxy or a lesser pool paint.

I have vague recollections of having heard of people sanding pools -- it would be tedious, but if your remaining plaster is thick enough, it could probably be done using flexible diamond disks. I have had some diamond disks that would work, but those pads are no longer sold. I'm sure there's something out there, but I have no idea how much it would cost or how long it would take.

Sorry!