stain or scale just won't go away

I've tried the test kit from Jack's Magic, and it did not definitively remove the scale. The scale just appeared over the winter in my mesh covered (formerly white) plaster pool. All the chemicals and chlorine are balanced. The pH was a bit low when I uncovered and it didn't take much chemical to resolve that. The water is nearly crystal clear. I'm using a sand filter and keeping the pump on 4-5 hours a day to keep the chlorine up.

The pool is fine otherwise. I'm in Austin and it's 100F everyday. Is it getting revenge on me for covering during the winter?

Obviously, without seeing it, and without test results, we really can't tell anything.

Can you:
#1 - take pictures (mail them to poolforum AT gmail DOT com)
#2 - get the best test results available (dealer?)
#3 - get a Taylor K2006 or 2006C so we can get GOOD test results.
#4 - list the different chemicals you've used over the past 9 months (going back to the end of the summer 2010)

Unfortunately, I don't know what's in the Jacks Magic kit, so I don't know what you've tested. One test you might want to do is to put a bit of the scale into a covered glass half full of white vinegar and let it sit overnight, to see if it dissolves or not.

Thanks PoolDoc. First thing I'll do is the scale test in some vinegar solution (acid) as you suggested. That is an easy test. I'm swamped at work. I'll post a pic in the next 2 days. It is tan colored. We pretty much had a perfect pool since it was resurfaced in 2004.