Fortunately we discovered this website and Randy's DIY supplement while we were still on our first bottles of B-Ionic. The tank's thriving and our total supplementation (Ca, Alk, Mg) is about a dime a day. I have to mix Ca and Alk about every other month. Mg should last about 14-18 months.
What I don't understand is why local LFS's don't pre-mix and sell it for enough to profit, but still less than commercial products. There's a lot of room for profit margin. Seems like a win-win to me.