How do you maintain your MAG / CALCIUM levels

[Lampshade]

I run a calcium reactor for calc/alk. For Mg I picked up MgCl from walmart, found the MSDS sheet for it and it's got the same or less in terms of "extras" as the MagFlake posted on randy's DIY recipie. I add that + epsom salts(MgSO4). I use IO salt, and it's natuarally low in mag, so I'll be adding some of my Mg mix in every water change.