Kind of hard to tell with out a photo. Maybe someone sprinkled sugar on your plants as a joke. Give me a while. I will come up with another guess. As for the slow growth. I am thinking you are a new grower. Most new growers over water, over nut, just about over everything. Maybe try laying back on the watering. But then again, this is just a guess, because not only do we not have a photo, but you gave no information on your set up and such.
Ah yah. I know what those Crystals are from. Little Gray Aliens came in late at night and piss'd on your plants giving them Space Herpies.
Give these people more info. I bet someone will nail it down.