Magnesium plays a pretty important role, it's worth the cost of the kit.

I don't disagree at all....its just there's 2 schools of thought right? Those that test and dose everything, and those that don't over analyze and just do WC's and have no problems at all blissfilly unaware....I'm not sure which I'm following yet (low maintenance is key)....now that there was a reply about natural seawater being 410/7dkh I'm not as worried about it, because I'm in the norm :-) still would be nice to know what it is for the sake of knowing.....

I really didn't mean to pull this thread off its original track so please back to calcium/hardness :-)

A thread goes where it goes, that's why it's called a disucssion board. ;) A discussion about calcium and alkalinity without magnesium is like discussing water and earth, but not air. :p