Is there something wrong with my rockwool?

Hey everyone, newbie here, I just came across some dark reddish/orange stuff on my rockwool where the water was dripping through my drip system (using a DWC/Bubbleponics).

I was just wondering what this stuff is and is it bad? I would think it's from the Hydroton rocks but I rinsed them pretty well before using them. This happened overnight and I didn't notice it until right now.

Here's a pic, I scraped away most of the dark stuff already

Probably just from the hydroton, and it shouldn't be an issue, I have the same thing in my setup. If you're refreshing your reservoir weekly it shouldn't be an issue

if it stays that wet the whole time you will end up having problems...

its definitely from the hydroton ... IMHO ditch the hydroton and just use rockwool chunks!