Two 18 watt uv sterilizers, an utraviolet light that the nutrient passes through to sterilize the nutrient solution.

The tops of the containers are made out of 1 inch thick polyurethane foam, the pink stuff at home depot. I cut a donut shaped piece out that fits snug inside the top of container and a larger one that sits on top of it with a 6 1/2 inch hole in it, a 6 inch net pot that usaully fits on a 5 gallon bucket sits in the hole. The roots wrap aroud the drain pipe inside and you cant rip them out once their established. getting ready to run again. i will take Pics of the whole thing and post em, Peace and thanks for the good words!!