Nice pico. It would be interesting to see how the UG responds to such a tiny environment in there.
Out of curiosity, are you planning to maintain this over the long term or is it more of a "fill-in-the-cube" kind of thing right now? I noticed that you don't have any sort of filtration over this and I already spy some surface scum forming in the first picture. I've actually kept a pico like this before, but quickly decommissioned it after a few weeks because I found it was just too much of a daily hassle with the inadequate filtration and its associated consequences.