It does seem to hold most of the water in the lower bucket and protects the scoby from getting used up as well, as will happen if one accidentally feeds out the whole bucket before refreshing it. I'm using a single bucket right now and I'm still getting the same results, so it's not entirely necessary to use the double bucket. I'll tell you one thing that I do that may make the difference. Each day I open that bucket, I stir it very well, bringing the more moist feed at the bottom to the top(I stir it with a scoop, so it's like a digging motion with the scoop facing me) and making sure the dry at the top gets well moistened with the fluid from below. This keeps my drier feed from getting moldy and it also redistributes the fermented water each day so that I don't work from dry towards the soupy on my bucket. Then when I scoop out to go feed, the feed I'm scooping isn't too dry but also isn't sopping wet...it's just right. It's sort of like eating a bowl of cereal so that you have a little milk in each bite so that you are not left with no cereal, and all milk, at the end. Here's a few vids of refreshing the double bucket and you can see what consistency I feed it at in the warmer months(in the winter time, I feed it drier). It helps that my feed trough has holes drilled in it to allow the excess moisture to drain off if need be.