Thanks for the replies.

I'm pretty sure you're all right on the mark. I think it is calcium scale. I went swimming tonight with a snorkel mask and inspected most of the pool. The surface is extremely rough (feels crystaline). It covers the entire pool, other than the foot or so that was not under water over the winter (that part is smooth). On the bottom, and all steps, it is tan, and on the walls and vertical surfaces it is white or colorless. I have a Merlin mesh safety cover that lets in fine silt over the winter so I think what I have been calling stain is actually dirt-covered calcium scale. This did not happen in prior years, but I don't remember opening at such a high ph level before.

I am willing to do whatever it takes to get rid of it. I would like to try every alternative other than draining the pool. The pool is appox 28K gallons and costs ~ $900 in fill water to fill it. I'm sick to my stomach because our pool plaster has always been baby smooth and now it feels like volcanic lava.

I will first try dropping the PH to ~ 7.0 and do a lot of brushing. So far brushing doesn't seem to do too much. I only have a nylon brush, should I buy an aluminum one? Is there anything else I should be doing? I don't know that a pumice stone is an option. The scale seems to be on every square inch of the pool.

Btw, my cya level is ~50.

Thanks,

Pat.