Product review (1 stars): moldy
This is the 2nd filter we bought this winter, our last one we got less then a month ago, put in 2 weeks ago and it is covered in black mold. We change the water every night and use it 12+ hours a day so the water isn't just sitting. Maybe it is the humidifier itself- I don;t know but our other humidifier with a different brand filter works and doesn't get moldy.