Hi all few quick questions I see everyone posts talking about worms. So I was wondering what kind of worms most use, how many per bed (I'm using ibc chop 2), and my media is lava rock will this harm them or will they be ok with it? Ok last part is what is best for tilapia food? Can they survive on a duckweed diet or do I have to give them other sources of nutrition as well? Thanks for all you input in advance!