Quote Originally Posted by colour
What about putting visqueen plastic around the rockwool and poke holes on the bottom for the water to drain...? That make sense?

-Colour:hippy:
I would avoid doing that. The best thing that rockwool's got goin' for itself is the ability to retain water and plenty of air for oxygen. If you plastic the cubes, they will not drain properly and your setup will fester.

I would also drop the light directly on top.

Take the remaining with a grain of salt:

I used to use rockwool for germination and rooting cuttings. When doing either, I never checked the pH. I found that since the seedling is supplying it's own nutrients, and the cutting can't absorb any, the pH did not matter since pH of a media is most important for nutrient uptake. If your main media is rockwool, if you're going to have your mature plants eating nutrients from rockwool alone, pH is very important and is best tested on a sample from the block itself.

For seedlings, I have also always used a 1/4 strength nutrient solution when watering.