Can some one tell me what this is....Pix

I have had this rockwool covered with a saran wrap colored black because I heard the top of the wool can get fungus/mold if exposed to light tell me what I should do peeps this is first dwc i am a soil man.



The strain is Northern Soul.

Bump......

Nobody knows what that is...Hmm

Could be from that paper wrapping around your rockwool (Grodan?) ...I always take mine off.
I was never sure if you should leave it on or not.

it looks like mold to me. are you using H202 in your water?

Fungus! LOL

I have 3 airstones in there on two pumps

well I cnat tell for sure. if it is not fuzzy like mold, then it could be calcium from hard water. but that take a while to build up, and generally starts out almost powdery looking on the hydroton. take one out and pour some hydrogen peroxide on it. if it goes away its mold.

Just take the plant to the bathroom and examine it closely. Rockwool does get weird sometimes but usually nothing unless really bad mold i wouldn't worry. but if you cover it for light purposes make sure you use a breathable material. Sounds like mild mold because no air circulation under the suran wrap. just rinse and cover with something breathable. good luck

it also could be salt buildup from nutes. if its kinda white hard powerdery stuff. like white salt

I am with 1982, I have had that happen to me, never worried about it, the plant looked fine. It was from getting wet with nutrient water. Next time I did a water change, I changed out the hyrdoton as well and I went on down the road.

Looks like limescale, why dont you just remove and replace the mouldy pebbles?