Between 55 and 62% humidity, it took six weeks for this tiny thing to fill. What really chaps my hide is that the power converter in the middle of the cord measures about 3"x4.5"x7", which totally negates the compactness of the unit for me, and pretty much defeats the purpose of the long cord. It's two units to think about when placing it it in the tight spaces for which it's purposed. In short, it's ineffective, and much bigger than I expected.