in my failed moss tank, i tried using a pc fan with the plug "snik"ed off with wire cutters. i wanted to use a humidistat, but i didnt have one, so i just soldered the pc fan to the wires on a AC to DC power adapter. it had a switch adjustable from 3 volts to 12 volts. i attached it to the mesh top right on top of a hole in the cellophane that i put on top of the cover, the "air intake" then i cut a same sized hole in the opposite corner, the "air output". i wold turn on the fan when the tank was too humid. i was afraid that if i left the fan on too long, or permanantly (even on the lowest setting) thas the moss wouldnt have enough humidity to sprout. when i first saw the damp off, i permanently kept the fan on the lowest setting, and tried to eradicate it with a homemade "fungicide" of very diluted hydrogen peroxide . but by then my tank was overrun. it was too late. my cape sundew was lucky to make it out alive...