High magnesium


Leigh Ge

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Aug 17, 2020
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Mount Gambier
So here’s a question. I’ve had a reef tank for just over a year.
When I first set it up I was using natural sea water and all my parameters were within the accepted levels for a reef tank and my corals were thriving.
When winter came, I switched to Aquaforest Reef Salt.
As part of my weekly routines, I would test my tank water and my magnesium levels have been in excess of 1600. I’m using a Red Sea test kit which only goes up to 1600 so I don’t know the true level.
After months of frustration and declining corals apart from one of my Duncan’s and some morphs, I’ve completed a series of tests on my water for magnesium at various stages as below

fresh RODI - 0
freshly mixed at 1.025 with Aquaforest reef salt 1600+
tank water 1600+

other parameters are:-
A - 0
Ni - 0
Na - 5
Calc - 420
Alk - 8.2
PH - 8
Phos - 0.03

in conclusion, it has to be the Aquaforest reef salt that’s causing the high magnesium.
Ive also found a few articles of other people complaining of the same results with Aquaforest reef salt
couple of questions if anyone can help
Will high magnesium cause a decline in coral health over an extended period
Any recommendations for an alternative salt, thinking of Red Sea blue bucket to try and bring my parameters down to a normal level
Top Shelf Aquatics


7500 Club Member
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Dec 16, 2017
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Red Sea is good . Fritz is a cheaper alternative

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