Mold growing on my rockwool?

Hi,

I'm using rockwool cubes for the first time and I have some mold growing on it- should I be concerned? If so, how do I fix this

Cover them with a heavy paper and cut a piece out with a little opening to go around your stem, this way no light can beat down on the rock wool cube. As for getting rid of the current mold I'm not sure which product is best for that. Will be watching your thread to see what some other experienced growers have to say.

H2O2, hydrogen peroxide, horticultural grade 35%, mixed at 1-2ml per quart. 2 or 3 applications of that should kill whatever it is.

HTH