I have a Pinpoint Calcium Monitor Big D you are welcome to use. It is a bit tricky to get right, but it does give you a good idea where you are sitting.
Darren,Yep you got it. The trick for me what to figure out how much they can fit into two boxes to minimize the shipping fee. I got bulk 16 cups of the Ca and Mg each which maxes out one box. Then in a second box I got the 12g or 6g kit. I cannot remember which size. Just make up a couple shopping carts and find the "sweet spot" as far as shipping goes. It is a good deal... much cheaper than LFS however you can get a terrific deal if we could find DowFlake and Mg Flake bags locally.