Salt build up?

[Benelli]

This is my 3rd grow with fox farm soil and never had this problem and just noticed it. On the top of my soil it looks the sweat stains on a black shirt...if that makes sense. Is this some sort of difficiency? It is weird because I have never had this on previous grows and all things are equal. Thanks.

 

[McFonz]

Could you get a picture?

 

[bird mcbride]

This is my 3rd grow with fox farm soil and never had this problem and just noticed it. On the top of my soil it looks the sweat stains on a black shirt...if that makes sense. Is this some sort of difficiency? It is weird because I have never had this on previous grows and all things are equal. Thanks.

Are you using a different water source?

 

[Benelli]

Same water source. I always fill my gallon jugs and let them sit out for a few days before I use it.