I have been using the same home built system and I will give you some findings. Depending on the pail, you may not get a good seal between the two and your family will complain about that rank smell.
PROBLEM #1
I used some weather stripping seal between the two that was placed on the top filling bucket in the lip that rests on the lower one. The family is again happy and mud room scent free. I did not add a drain as you can just pull the top bucket up.
PROBLEM #2
When the bucket gets full and used a few times, they are REALLY hard to separate to drain the Bokashi Leachate into another vessel. It creates a bit of a vacuum and not at all easy to break, especially when you pour out the leachate and put the pail into a wet lower pail.
Potential fix in testing. I had to make another Bokashi pail system last night and this time I did not place the weather stripping into the rolled lip on the upper pail but wrapped a wider weather strip piece I had about 1/2 inch lower so the upper bucket would sit on that and not fully seat so the vacuum would be easier to break. I also cut down a yogurt tub to ba a spacer in the bottom to prevent total weight of a loaded pail sitting on the pressure sensitive weather stripping seal. Time will tell.
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So now I have four systems on the go and remembered Andrews blue barrel. I need one of those! But do I need to wait until I have let it all ferment in the 5 gallon pail or can I just dump in into the blue barrel once full, pack it and cover with a plastic bag to keep it anaerobic below until next load? or would you recommend doing a two pail system where when both are full and the first one has moved along, it goes into the barrel and cycle through that way where at least it has a couple of weeks to brew before going into the blue barrel? if I don't get a big storage device, I will have a garage full of 5 galloon pails?