I use blue bucket a switch about a year ago, from i.o.reefcrystals (that i used forever only) not only because of the brown stuff but it was a high alk mix, I want to be @ around 8dkh now and I wanted a cleaner salt with out paying to much more.
I have been completely satisfied with blue bucket, but recently I got a bucket that had allot of brown usually its not so bad but this bucket is by far the dirtiest I've had yet.
I'm still using it but with the sediment filter trick I learned.
So I mix it up at 23°c with a internal pump sicce 1.5 in a 40g breeder tank, I add salt 2cups at a time very slowly in the current then after its all mixed by blowing the bottom of the tank around with the pump, I hook up a 1 micron sediment filter to the brs reactor and the sicce 1.5 and let it filter out and brake water surface for a couple of hours, then bring it to tank temperature.
The mixing at low temp and not having pump on for more than so long it to preserve alk/cal parcipitation. But I have noticed as long as its brought to mixture at low temps then brought up to temperature it stays around 8.2 pretty consistently.
I love the salt and when its on sale I stock up!