As far as the algae on the rockwool you are correct, just cover it. I use a little square of panda film but, anything that blocks the light should work. The little light on the aerogarden is better than you think, I can veg mine to about 8-9 inches in the machine. I have never put it outside but, don't see any problem with sunlight. Maybe bugs and neighbors... If you think that you need more light get 2-3 42W CFL's and add them to the factory light.