Slimy Green Rock wool?

Hey FMB, I am using a hydro setup right now and I am using rock wool as my growing medium. Today I check my plants and I noticed that some of the tiny rock wool cubes are turning into this slimy green stuff. Is this a problem? If so what should I do? And how do I prevent it from happening again?

P.S. Could it possibly be algae?

Thanks,
BMN

it will not effect your plants...its a green algae that grows on the rockwool, one way to stop it is to cover the rockwool.....but yea it won't really harm the plants

Cool, Thank you fullmeltbubble. =)