Product review (3 stars): Most-recently purchased wick filters from Vornado are quite different!
I don't know where the fault lies but in the more than 10 years since I've been using my Vornado with the two 4.2 gallon total tanks I've never had the problem with filters getting as discolored (and what that means?) as those with the metal inserts and/or with using the original BestAir's Golden Solution.  Until then the most I have ever seen on the wick filters was the build up of mineral deposits which I've been able to successfully remove with a water & vinegar soakbe advised that a too-long soak will turn filters to mushafter which I removed as much water as possible and stored them at a very low temp (to deter the growth of "undesirables") while completely new wick filters were in use in my cleaned and disinfected unit. That was a single year's strategy; I had never previously, and haven't since, frozen a soaked wick filter. Note: I'm not commenting on what freezing does to the aiding-in-humidifying quality of the paper in a wick filter.

I've gotten filters here as one-time purchase and under amazon Subscription that were supposed to be identical to Vornado's originals, and elsewhere from other well-known manufacturers of products for humidifiers, and I've always added to the tanks a product to deter algae, bacteria, and mold growth and soon began adding a much-needed separate solution for mineral deposits. (Btw, are they necessary? Yes! In the less than 24 hours that my unit was turned off until I could address the filters conundrum the solution lying still at the bottom began turning green at one endmore light exposure therewhile it turned yellow elsewhere.)  The top was removed and the wick filters (which contain metal and will be tossed partially because they sat for several hours) were left in place but nothing had begun to grow VISIBLY on the filters themselves within those 24 still-water hours.

My most-recent strategy of daily flipping and then switching of the front wick filter to the back and vice versa (since the back side is closer to a wall) gives them equal exposure, to both air and water in the unit's bottom tray, and seems to allow them adequate time in the bottom solution to keep them from solidifying with mineral deposits. Few people have that much determination or time to devote, but visibly improved health dictates use of a humidifier 24/7 once the heat is on.

Only because I had two different brands of filters on handdue to what you see in my photoswas I able to compare them, and there's no doubt that the&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Vornado-MD1-0002-Replacement-Humidifier-Wick-2-Pack/dp/B000E1385Y/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Vornado MD1-0002 Replacement Humidifier Wick (2-Pack)</a>&nbsp;is largerwider and more densethan the supposedly identical replacements because I had to use pressure to get each into the space those other "replacements" never fully-filled, AND at this point of purchasevery late Dec 2017there is no metal supporting mesh in the center of each Vornado wick filter.

I may be wrong but I have suspected a chemical reaction between that metal and/or the solutions I've used because I've never had any color but shades of yellow on wick-filters before.  I briefly-entertained the possibility that soaking it in vinegar and possibly not fully removing it had left it open to reaction with either something in the wicks themselves (the metal? a different paper?) or the Golden Solution. But I have used no vinegar so far this heating season which rules that out.

I will post again once I see how these newly-purchased wick filters from Vornado perform using&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/BestAir-3BT-Original-BT-Humidifier-Bacteriostatic-Water-Treatment/dp/B000CMHLMG/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">BestAir 3BT, Original BT Humidifier Bacteriostatic Water Treatment</a>&nbsp;and&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Sunbeam-Humidifier-Water-Treatment-Solution/dp/B007J24VDY/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Sunbeam Humidifier Water Treatment Solution</a>&nbsp;both of which were also newly-purchased.