How often should we change wick filter? Do not understand metal support layer facing out. Is this toward the air intake on right side of unit? We have two wick filter replacement to cut and install. Should the wicks be back to back with soft sides on inside and metal support layers on the outside? We have no owners manual. Item was regifted to us as used. Sometimes fan will not come on after water filled and controls properly activated and fan cover properly seated. I bought a 32 oz bottle of bacteriostat to reduce bacteria and algae growth. Thank you, Dwane Wills Overland Park, KS 913 206-7112 (Cell) 913 649-6806 (Land Line)