We used to do a flood drain table but switched to a bubble tray for the smoother transition although the flood drain table did work we had much better luck with the pretty white fuzzy roots being present as they go into the uc. The roots do get tangled but more so in the stones and air lines than with each other. We got advise from Desert Squirrel aka Quantum 9 on the bubble tray design specifics. (Thanks buddy its working great) It is pretty basic but has a little twist to it or current rather from 4 pumps on each corner pointing circularly toward each other.
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So these are the pumps we used and with them comes that fitting with the little nipple on it. (I always wondered what it was for) Turns out that nipple is for a airline so you can get some extra oxygen into the current flow. If I could lift the top off my tray and take a picture for ya I would but that tray is just off the hook right now. Maybe later on I will see if I can get someone to help me out and I will post some pics. Other than that the tray just has the gray cylinder shaped stones that came with my UC system. I think there is twelve of them total on a manifold connected to a air force pro 40 which also came with my UC. I do believe that DS aka Q9 recommended a air force pro 80 for it but the 40 is working rather well. One thing that makes a ton of sense to me now but I did not think about until someone mentioned it to me (thanks again DS Q9) is that all of the air lines need to be the same length from the manifold to the stones or the air will not be distributed evenly through the stones and the hose should shrink the closer you get to the stone for the pressure. I hope this is making sense. You can hit me up about it if not.
I am also curious if you cut em down or not. I know first hand how very very difficult that can be to do.
Oh and dyna bloom and IBA in the bubble tray will make super white fuzzys fast like. I think DS has a thread about that.