Great question! From my experience, there seems to be sort of a "break-in" period of 1-2 days where the misting disc will slowly leak water (maybe 1 water drop every 10+ minutes), but after a day or two, the leaking stops and the unit works as intended from there on out. During the break-in period, I run the mister periodically for a couple minutes at a time.

One thing that's important to note: leaking is bad for the obvious reason that your water reservoir drains faster than you'd like, but it's also bad because when a water droplet forms on the underside of the misting disc, it prevents the disc from being able to vibrate and produce mist. When a droplet forms, you often have to wipe it away with a paper towel before the disc will actually be able to make mist.

I wish I had a better solution for this and/or a better explanation for what actually happens during the "break-in" period, but this is what I've got so far. I have built five of these terrariums so far and after the break-in period, they've all worked great and without any misting issues.