I guess this means I need to change the remainder out and mix a new batch of mag supplement...
growing in my Mag
Probably kryptonite
Could be calcium sulfate which often precipitates from mixing magnesium chloride and sulfate salts, but the single crystal nature is very unusual, implying very slow crystallization. Habib's evaporation hypothesis seems pretty reasonable as that is a prime way to get big crystals.
I have some from the moon but that is green colored and very expensive/rare.
Now Randy, how the heck would you make calcium anything from Mag sulfate and mag chloride?
Reefing alchemy? :lol2:
IIRC there is also a red form which had the opposite effect.