Product review (4 stars): Good info on humidifier filters!
heres the scoop...in agreement with all here but more facts: mold spore hotel for all filter brands inc honeywell.  you need 2 to keep drying out one used previously. flip the placement nitely too then bottom.  soak in warm water to clean when usung 2nd filter. i use a baby shampoo n let soak briefly litely rince then stand up to dry..not letting sides touch.  the pop honeywell is very easy to clean. i use white vinegar but honestly if you dump water everyday. dry..bacteria cannot grow. sunlight is natural UV moldspore killer. i live in dreary new england where 6 outta 10 days are cloudy. set filter in sunlight on your window sill or enclosed porch. i also noted poochy smell coming off filter. its bcuz of dampened material. im super mindful of taking apart daily..but having 1 filter..it never dries out fully by nitefall.  its growing spores..time to buy a 2 pkg. oh btw, if youve got soft water itll turn color like brownish pink on edge mtg water trough. if hard..dunno bcuz ive got soft.