I dont know anything about cow but I would think you could start a new tray especially if the top tray now is dark and looks like coffee grounds. You can take some of the leftover debris to start the new tray. If you have 3 trays going at the same time it would be pretty easy to tell how its going . The bottom tray when nearly ready would be mostly dark and look like coffee grounds and even if there is some debris but not a lot of worms in it you could harvest or wait another week or so. If you only have one tray going your would always be adding debris when you feed , at least thats what I do. When I first started my factory 360 I had about 1500 worms and when it got to the point some worms were venturing out I then added my second tray. Its sort of a learn as you go, mistakes will be made but thats ok and you learn from it. Good worming.

smdmt, I too would like to see all my castings having that look of pure coffee grounds but I think I'm too impatient. I say, start a new tray and harvest some castings. Either put unfinished stuff in with the new bedding or just use the castings as they are and let your garden microorganisms finish the job. After all, why should your worms get all the good stuff?

Harry

Thanks for your suggestions!

SMDMT - I start a new tray in my work factory when the feed tray is full to withing 1 inch of the top. After the worm have finished with it, it is a little less than 1/2 full of worm castings, call it 3/10ths full.