so about a week or so into my first hydro grow. ive start noticing some white patchs on the hydrotons. im around 5.8 ph -1+1 , no nutrients added yet. Using Tap water left out for 24-48 hours with 50 PPMs ive heard it can be salt deposits but the first photo is the rocks 2 days aago. this freaked me out and i thought mold right away then i decided to changed the rocks on the spot, cleaned them from the dust , and re-put them back into the net pot slightly wet. this is now what i have 2 days later/ slight white patchs. have you guys ever experienced this in dwc?