CoralifeSalt Mix Issue

[fio1022]

Ok,I don't know where else to post this so I figured I'd give it a try here.
I've been using Coralife salt mix for three years without any problems.Actually quite pleased with it.I have a 50g salt mixing container that I use for an Automatic changer.I mix a new batch monthly.Water is aerated daily with each water change(1 3/4g daily).
I've noticed than when I mix a new batch,there is a brown residue on the surface.I do my best to remove it but still some of it remains.
I just cleaned out the entire container after almost a year and sure enough after mixing up a new batch more residue.
Any ideas what the residue is,what is causing it or how to prevent it?
I hoping not to change brands
Thanks in advance.

[Percula9]

It sounds like some sort of insloluble additive. I have used that salt in the past but never noticed any residue after mixing. I have since switched to oceanic because coralife is high in borate.

[bertoni]

Does the brown residue show up right away, or does it form over time?

[fio1022]

Right away,In the time it takes to mix.I try to wick it off but I can only get so much.

[Billybeau1]

I have used Coralife in the past with no such issues.

I would get another bucket and see if it does the same thing. If it does not then I would return the original bucket for a refund.

[bertoni]

I'd return the salt, personally.

[fio1022]

Not just one or two batches.This has happened with every bucket over the course of three years.I don't see any ill effects other than the residue left behind.

[nietzsche]

i get the brown stuff too, so does my friend. he thinks its because the powerheads bring some kind of bacteria or algae with it from the tank.

we both use reef crystals but havent noticed anything bad about the brown stuff