Tropic Marine Salt mix.

[ReefRaff]

So I mix up the water and let it set a few days. I always get this white residue that seems to leach out and settle on the sides of the contaner, pump, and heater, when it sits and mixes for more than a day or so. Is there a reason for this? could this be calcium precipatating out?

I use the water and all turns out fine, but just seems wrong.