That's really puzzling that your pool water would produce scale. Have you confirmed that's what it is? Does acid foam up when you apply it to the scale?

Nothing in your test results (thanks for posting those) would indicate anything far enough out of whack to give you any problems. Has your pH slipped up over 8 this Summer?.....not according to your description...hmmm.

That's really a puzzling issue and I hope you discover the cause so we can all learn from it. Sorry I have no suggestions.