There are many chemical manufacturers around. Important thing is to find out the purity of the magnesium chloride.
I bought a 25kg sack from:
International Scientific Pte Ltd
33 Tanjong Penjuru
S(609029)
Tel: 62611744
Email : sales@ispl.com.sg
Their Mgcl properties :
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SPECIFICATIONS
THE FOLLOWING SPECIFICATIONS REPRESENT THE TYPICAL, AVERAGE DATA OBTAINED FROM ACCEPTED TEST METHODS CONDUCTED AT THE PLANT:-
MAGNESIUM CHLORIDE
MgCl2.6H20 96% min
MgSO4 2% max
NaCl 2% max
Descriptions
- soluble in water and alcohol
- deliquescent crystals
DUE TO ITS HYGROSCOPIC PROPERTIES, A SLIGHT DEVIATION OF 1% MUST BE TOLERATED.
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They sell in sack form. You need your own transport to carry. Also, the magnesium chloride will melt upon contact with air as it absorbs moisture. So what I did is to put into ziplock for every 2kg. 2kg can last at least 6 months for my 650L tank.