In deed, sometimes y-tong produce salt if it is a long time in water (not always) and as far as i know it is not bad for the ants.
I'm do not know much about mold Azzer, so i can not say if this is mold ore salt coming out of you farm. Maybe you can try some natural fungicide, like lowth01 said.
@ azzer: that is im afraid to say definitely not salt and it is mold which can be easily recognized by the growth, natural fungicide might be a good idea and if it does get into edible range of the colony then the water should dilute it enough to become harmless.
@jimmy: salt isn't bad for ants as long as the don't eat lots of it.
Sithmaster676