Mg, NH4 and new ASW

dallasg · Dec 22, 2014

Hi Randy,

on our local forum there is a discussion about salt mixing and high Mg salts that can cause NH4 in the new water. the salt is Seachem Reef Salt. is there any truth in this? what could cause MgCl or MgSO4 to create NH4 in new water?
is this even possible? the water tested fine after loosing 2 tangs, any ideas?
the water was made and used within 1 hour of being mixed to the correct values for an emergency. could the deaths have been a result of low DO in the new water rather than ammonia?
the gent who made the comment did say it was Julian Sprung who told him this

TIA
dallas

Randy Holmes-Farley · Dec 22, 2014

Magnesium doesn't create ammonia, but magnesium chloride may be the source of some of the ammonia in salt mixes as it is a known impurity in it.

For years, Seachem's magnesium supplement didn't contain any chloride and was just magnesium sulfate for this reason. However, there are suitable sources of magnesium chloride available, at least for magnesium supplements. These grades may be on the expensive side, and higher magnesium salt mixes may necessarily bring in more of this impurity, even with the better grades.

If you didn't detect ammonia in the water that the tangs were actually not (not just before they were in it), then I'd look for a different cause for the tang deaths.

If you stirred it to mix it, i doubt low O2 was the problem if the tank itself also had reasonable aeration.