Reef Salt turning blue

[ndz98]

I’ve had this bag of salt for probably a couple years now and I’ve noticed that it now has a blue tint to it. I’ve also noticed it takes more salt to get to the correct salinity and there’s always a little salt left at the bottom. I use a power head and heater to mix it up. Is it normal for salt to have these problems? Do I just need to toss it and get fresh salt?

 

[Big G]

Bump

 

[Randy Holmes-Farley Verified Community Expert]

I wouldn’t use salt that was turning blue. It sounds like copper contamination is a distinct possibility. It might be ok as color is not a good gauge, but not many things will turn it blue.

 

[dave001]

Ive just got this same issue. I only have a nano tank so usually just grab premixed from my lfs but keep a bag of instant ocean for "emergencies".
I noticed the colour had changed and its also not mixing very well at all with white particles floating around and its still very cloudy. My thought was copper too but I just cant see how any could have gotten in there. Yes the bag had been opened, but it was taped back up and folded several times. Moisture ingress? sure is possible, but copper?? I didn't ever consider salt might have a shelf life!?!?
Any other opinions on this?
Im going to throwing out anyway, but hoping a friendly chemist on here can tell me whats up!!

 

[Randy Holmes-Farley Verified Community Expert]

Blue is a mystery, but cloudy with particles is more normal for older or opened salt where calcium carbonate can precipitate.