I live in a basement apartment and tend to have moisture issues. With pico tanks, I tend to not go through salt mix very rapidly and no matter what I do, I seem to end up with moisture contaminated salt before I make it half way through (usually the end of summer). Sealed bags in sealed buckets with multiple large silica packets don't seem to help in late summer. I'm about ready to switch over to ESV just to not have this issue anymore. This last batch was mixing up fine despite the moisture in the mix. I would just have to add a little extra salt due to the increased volume, but the calcium was around 420 and magnesium was around 1300 and it was mixing clear (35ppt). A little lower than normal, but still acceptable. For what ever reason I decided to try to dry the mix out by placing it in front of the heater. Now when I mix up some water, there is precipitate and parameters are lower, Mg <1000 and Ca <350 and I need to run the water through a fine sock to clear the water a bit before adding to the aquarium (as well as dosing to bring Mg, Ca, and alkalinity up). I left the bag there and it has gotten worse. I have not tested yet, but the bucket, pump, and heater are covered in precipitate. My question is, does heat effect the formation of calcium carbonate in the damp salt mix or was there some anomaly that caused the top layers to be okay while the lower layers bound the calcium and magnesium? Do you think mixing the salt for a bit before plugging in the heater will make a difference?