I'm using Reef Crystals and have similar issues with low alk. My parameters are the same as PKelley with the exception that my calcium is 460 and my Alk is 6 dkh (As of last night). I'll test my Mag tonight but last time I checked it was fine (albeit this was maybe 4 months ago).
If the Mag is fine, does anyone have a link to making/using the baking soda method of raising alk?
If the mag is low, where is a good place to purchase magnesium sulfate or are there other options to raise mag?
Either way, I'm following along.