I put 2" or so of pearlite @ the bottom but clay balls I think would be fine. I use 5gal, fabric pots. If you have a real flood tray they won't be sitting in any water. I flood 2 times for 30 min. each. Well a complete flood and drain takes 30 min actually. Don't be afraid to use some bio char or couple hands of worm castings in it either. I try and fool it to thinking it's soil instead of coco. haha funny I know. I have also put some of that rock stuff in the bottom as well can't remember the name of it real course grey color it's kinda like lava rock but small. They will grow in 1 gal. fabric pots but will suffer severely in yield. I've tried 1 gal pots myself, have used the baskets with clay balls. Been working this system for 8 or so years. So everything I have mentioned is things I have done and tried. Love to see you be successful!