Thank you for the link.Here’s a decent read on alk and calcium relationship.
Chemistry And The Aquarium: Solving Calcium And Alkalinity Problems
I hope this article proves useful is understanding and dealing with the different types of calcium and alkalinity problems encountered by reef keepers. Once you get calcium and alkalinity under control, you are far along the road to having your tank chemistry optimal for its inhabitants.www.advancedaquarist.com
I think I am understanding it now.