Updated review at January 3, 2024:After almost 1 month of constant 24/7 use of my 6 Gallon LEVOIT Smart Evaporative Humidifier for up to 3000ft², I learned from the company I purchase this machine’s filters from that the discolouration - even after just 24 hours of use - is totally normal and an expected result of filtering out impurities in the water used. So that’s a relief that it’s not growing algae on the filters. Actually, after using 100% distilled water in my humidifier for this past month since that first fill of municipal tap-water, the filters have not shown any further discolouration. So no doubt the distilled water will likely extend the life of the filters, and possibly the machine as well.But….after a cost-analysis of using Distilled Water vs, tap water in this humidifier, it’s more cost effective and practical to just use tap water.It would cost me $1,700 per year in Distilled Water (as the machine is averaging 32 Litres per week). So even if using tap water in the humidifier cause more wear and tear and build-up resulting in (worst case scenario) needing to replace the filters monthly (at $107.26 CAD including taxes and delivery) and yearly replacement of the humidifier at $346.50 CAD (includes taxes and free delivery), I’d still save $70/year and wouldn’t have to haul all the jugs of Distilled Water to use in the humidifier! So I feel it’s economically worth the risk to use tap water in this humidifier, and if I can stretch the rate of filter and machine replacement, I’ll save even more money yearly.I’ll update this review if I learn anything further. For now I’m extremely happy with my cute little robot-looking Humidifier I’ve named “Robbie”, haha!——-My original review:My 6 Gallon LEVOIT Smart Evaporative Humidifier for up to 3000ft² is already growing algae on the evaporative filter media after only 24 hours of use of this brand new machine.The humidifier was delivered by Amazon at 3:30pm December 8, 2023. I immediately unpackaged, filled it with tap-water as instructed and started it on the highest speed to see how long it could boost my humidity levels from their current 10% in my home and to see how it performs after going through a full tank of water.We’ll it sure does humidify the air really well in my 1100 square foot residence. Within just 3 hours my humidity went from 10% to 35% (I am using a separate hygrometer to determine the accuracy of the actual humidifier’s humidity gauge which does appear to be very accurate after 1 day of use at least). After 8 hours it was up to 58% humidity.It used a full tank of water (21 Litres/6 Gallons) in 24 hours of use on the highest speed by 4pm December 9, 2023. When I went to refill it, I had a good look at the evaporative filter media and it is already turning green in spots and the residual water at the bottom of the humidifier’s tank was very visibly yellow in colour.My municipal water in my city is among the very best quality water in the world (I live I Edmonton, Alberta Canada and we have award-winning water quality…and I work with water quality specialists who have confirmed this), so I observed the water was clean and clear going into the humidifier.I have since opted to fill the humidifier this time with 100% distilled water and I’ll see if it makes any difference to the algae growth I’m seeing on the filter.I bought this evaporative humidifier because of its claims to produce healthier humidified air as the filter is not sitting directly in water all the time - instead water flows across the filter and evaporates so the filter shouldn’t be growing algae - especially within just 24 hours of use!I’ll update my review when I’ve had a chance to determine if the distilled water is solving the algae growth issue with this humidifier’s filter.