Product review (1 stars): Molded quickly
I never had an issue with the Honeywell filter, but did have the browning, crusting. I bought the Pro Tec and Honeywell to compare. These filters molded with in 1 month of use. While the Honeywell HAC-504 did not.&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Honeywell-HAC-504-Series-Humidifier-Replacement-Filter-Filter-A/dp/B000RDAORO/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Honeywell HAC-504 Series Humidifier Replacement Filter, Filter A</a>.