Aeration / Acid Treatment to lower Alk

[Yeggim]

Scrape some scale off the side and collect. Put in a glass or bowl--pour some vinegar on it--if it's calcium it should bubble and/or fizz.

You need to get a good test kit.

http://poolsolutions.com/testkit-order-links.html

[Donski]

Some scrapings in a bowl with a few drops of vinegar and there was no bubbling or fizzing.