I built something similar to this about 3 months ago and damn it if I am not having nasty problems. I have the exact same tub even, did you get at container store? At any rate I think what the problem is that my cups (I use 2" netcups and star collars) don't sit on the lid correctly and leave pin holes. Notice how the lid undulates up and down in channels? You will find that once the holes are cut, you wont have a clean surface for the netcup lid to sit on and as such pin holes and slits are left behind. I have plenty of panda film and created a nice sheet to lay over the lid before inserting the cups, but that doesn't seem to work all that well either. I orginally tried DWC in this system and was able to get some clones rooted and into my system but I had to cut their stay short for fear of algae. I was having to clean the system every 3 days.

The second I filled the cups with coco. I watered once a day with a timer and let the bubbler go for 15 minutes. Total failure. Coco cant handle that much water. Then I emptied the cups filled with half coco and hydroton and failed again. Coco again can not handle that much water. I have a 3 head disk fogger which worked pretty well as I recall when I attempted to grow in fog when I first started growing in general. I learned that mature plants aren't easily grown in fog but clones are I found. I recall vividly how quickly those plants started to sprout. Hopefully I can find a way to make this little box work with a fogger now.

Please forgive the ugliness of my closet. That area has been flooded before and caused water damage to the baseboards and what not. Too broke to fix it all.