Product review (5 stars): Great Wick Filters
I purchased a whole house humidifier (Essick Air EP9 500 Whole House Evaporative Digital Pedestal Humidifier) that uses this wick and they are a good quality that work really well.

I use the Essick Air 1970 Humidifier Bacteriostatic Treatment (1-Quart has already lasted me 2+ winters) each time I refill the humidifier which keeps the mold or mildew under control.  So use one wick per winter season, however with that said, I do live in Houston, TX, so our winter season is obviously quite a bit shorter than northern states.