Hope some one can give me some answers...i hav a problem with these aphids, every batch i always end up having aphids coming out and crawling everywhere then they start to fly. Where do they come from, i use rockwool so it cant b from soil. i read somewhere that they form from the green alge i sometimes get on the bottom side of the cubes, but i dont kno if thats true. so i bought these covers for the cubes and there back this cycle. I dont like them cuz i get paranoid there gonna go back into the water tank and go through the drip lines and get them clogged. If anyone has a answer that will prevent them from coming back every cycle. Your anwser will be much appricated, thank u.