I moved my Earthboxes inside to the basement in hopes of growing veggies year round. Within a couple of weeks I began to notice a few gnats flying around... thought they were fruit flies. About a week later there was a cloud of thousands. Organic pesticide spray got rid of them temporarily, but now they're coming back. Notice they're attracted to the base of the plants and anywhere there's water (overflow area and filling tube). Have been told by a friend that they're fungus gnats. Is there any safe way of getting rid of them permanently? If not, will I need to completely get rid of the soil before I plant outside again? Any help is appreciated.