who mentioned soil - he said he had a spider mite problem? who's the pest?
he did, he posted the same thing at least three times maybe four. And we still don't know what his problem is. Sometimes folks don't give you all of the facts in one place. I knew from experience you can't see spider mites without magnification until you see webs and holes in the leaves. And spider mites don't fly. If I could see colors and match what he has described my guess would be fungus knats. What he should do to be sure is buy some traps, catch some of the bugs and take them to his hydro shop for identification. In the meantime he can buy neem oil, dish soap and mix his own insecticide, begin a weekly maintanance program and get rid of most pests, including spider mites and fungus knats. He should pay particular attention to the bottom of the leaves for the first couple of weeks, if conditions are right for fungus knats they are right for spider mites too.
I have been conducting a little experiment in my grow room. I like coco-coir as a medium and so do fungus knats. I have been leaving the coco-coir down about an inch or so when I transplant to my finish size pots and then putting flock rockwool on the top. I read the information on SM-90 and daita?????earth, both seems to cut the larvae when they try to surface. I thought the rockwool might have the same effect. I also thought this might be good for controlling algea. I haven't had to use any weekly maintanance for the last three months. Doesn't mean it works yet, its winter here and pests can't migrate to the grow area very readily. I'll let you know how it does in the summer. I am also going to try using sand on the top. I think both the flock rockwool and the sand will help to prevent any infestation. It won't let the adult lay eggs in the medium, they have a short live span and the adults are not doing any damage if the can't propagate. My uncle was the head of the Entomology Department at Rutgers, he addressed an International Convention in the 1960's. He always said the best cure for pests is prevention.
Now, are you beginning to see why I feel qualified to give answers, or do you need more schooling??