White spots on leaves: Hard water?

Hey guys, i think that my leaves are getting covered due to hard water. I thought it was mold at first, but then i noticed the same spots on my hydro tank where the water had dried.

Is it likely that it's due to hard water? If so, assuming i'm having no other problems, is everything cool?

Either hard water OR is there something splashing or misting on your plants? Like your pump or heater, something like that? If water is getting on the plants and doing that it's either hard water or the nute concetration drying up that is doing that.