Mixing a new bucket of salt red sea blue bucket with tap water ran through a Brita filter an tested the magnesium it's coming back to 960ppm using salifert test I mixed it per instructions even started it at 65 degrees and brought it up. I'd the issue the brita filter and not using r.o. water or could it be a bad batch of salt used two different salifert tests 1 is brand new one is about 4 months old both reading close to the same results.