Whats this stuff on my hydroton?

So I had too much water flowing onto the hydroton at first and it was keeping everything soaked, I moved it to the bottom of the mesh pot. The hydroton on the top of the pots is now relatively dry but the rockwool cube stays moist. Now that they are dry though they have this on them, what is it? It bad?




lol purdy nice pics for cell phone =P

nah, they're fine.

Looks like dried nutrients or minerals.

It's dried nutrient salt. Don't worry about it.

WHEW! Thanks everyone! Haha =P