[markem]

I use a white lint-free cloth that is washed with bleach and never sees the dryer (because of dryer sheets and their residue). For the 1.5qt, my wicks last about a year. Some source of mold must somehow winding up contaminating yours. Could be in how they are stored, how you clean the unit, how you store the distilled water or even a source of mold within the humidor itself. Hard to tell.