Comment by genewitch

I read the page because you linked it, as an aside " (Yeah, power usage goes down when you add the extra carbon filter to the IKEA purifier. I’ve confirmed this myself with a power meter. Physics is weird.)"

when you block a vacuum cleaner the motor spins faster and uses less electricity, it just sounds like it's "working harder" but if there's less stuff (air) there to create friction then it's working less hard. So the heavier filter material using less electricity makes sense, especially when you take into account the lower "CADR" - wtf-ever that is.

Furthermore , all of my "DIY" air filters do a remarkable job, and they move very little air compared to the fans they're duct taped to, but they still turn black if i don't clean them every month or two.