black algae on rockwool?

See attatched please. This a big problem? What to do?

Should I spray with h202? Why is some green and some black like this?

THis is why I use coco, don't use h2o2 it won't kill it. You need to use some bleach so the water has chlorine if you want to kill it. I use around 1 ml per 10 gallons of water of clorox 7% disinfecting bleach (DO NOT BUY SPLASH FREE KIND).

With test strips the 1ml/10 gal or 1ml/40 liters seems to hit 2 PPM of chlorine perfectly which is plenty safe for the plants..

Algae is going to happen, another thing you can do is buy some panda film and cut squares slightly bigger than the blocks and just cut a slit in it so you can put it around the stalks at the base of each plant. I've seen some guys who run the EBB & FLOW tables set all their blocks in a pattern then put the panda overtop and cut out the holes for the rockwool..

Rockwool and algae is like peanut butter and jelly. It's gunna happen.

i think the green is from too wet rockwool, are you flood n drain or nft or other?

It’s not a big problem, or any problem at all really. Ignore it.
light + heat + moist rockwool = algae. Fact of life.

source: rockwool grower since the 90’s, personal experience.

here’s a random 4” block from my garden after 60d flower. They go through all kinds of changes during the life of a plant. And yes, the dripper will be cleaned at harvest …

go go kid said:

i think the green is from too wet rockwool, are you flood n drain or nft or other?

Click to expand...

at the moment we are doing top feed drain to waste until the drippers are ready then drip irrigation drain to waste

right, just ive never seen alge on rockwool b4

Overgrowtho said:

See attatched please. This a big problem? What to do?

Click to expand...

Use some rockwool covers/prevent light from hitting cubes.

I think I will try the 2PPM of Chlorine Trick and see how it goes first...