Salt Mixing Problems

[Rog]

Hi,

I've had issues with my last 3 buckets of salt mix with calcium and/or magnesium being really low, cloudy water and precipitates.

I use RO/DI water, checked with two independent TDS meters. Input is 6ppm, output is 0 ppm. The cartridges are older but they still seem to be working well because of our low input TDS and exclusive use of cold water as per the manufacturers instructions, I presume.

First two issues were with Seachem Reef Salt. I've been using it for a few years without any problems. All of a sudden there's a white precipitate on everything in the mixing tank. Alk was way off. Tossed that batch. It was the end of the bucket so I drained and cleaned the tank and started on a new bucket. From the new bucket Calcium was a little low at 400 and Mg was 1050! Seachem support said that the minerals in the bucket may have settled and the roll the bucket on its side. I thought I would try that, but with a brand new bucket of Salinity this time. Drained and cleaned out the tank again and refilled with RO/DI. Double tested, TDS: 0.

I shuffled the contents of that bucket of Salinity into three other buckets, rolled it around, and poured it back into the original bucket. Figuring it was now well mixed and safe to use. By now the temp in the mixing tank was 17C. Each cup of salt was fully dissolved before the next was added. Water was a little cloudy, but eventually cleared after each cup. As I neared the end it stayed a little cloudy. Woke up this morning hoping it would be clear, but it is now so cloudy I can't see through it, again with a white powder precipitate on the bottom

The test I did on it last night showed:
Temp: 24C
Salinity: 35 ppt
Sg: 1.026
pH 8.65
Mg: 1080
Ca: 350
Alk 3.34

Wondering if it was my test kit, I went out and got new test kits and even borrowed the store's (a different brand) and confirmed the same results. According to seachem's website, my lot number 76409.00 should have

Salinity: 35 ppt
Sg: 1.026
pH 8.6
Mg: 1402
Ca: 430
Alk 3.3

http://www.aquavitro.com/retrieve_jp..._search=Submit

Turns out this is a rather old lot 12/7/15 the website says.

I'm getting really frustrated and really need to do a water change. Anybody have any idea why this keeps happening?? Either there is Magnesium missing in my bucket or something that is preventing it from being dissolved. I live in an apartment in Vancouver so I know C02 can be a factor and temperature can too. Maybe something screwy with my DI affecting Mg?

I welcome all of your ideas and experiences.

Thank you all in advance!

Cheers,
Rog