I would still choose whatever you think is the better product, 10% carbon on a ~4kg filter is 400g which is less than $20 worth of material.
The weller has a remote switch which is nice, although slightly lower claimed flow rate. Noise levels hard to tell as they don't give full spec, just "<50dB". Hakko filters seem to be cheaper.
I was wrong about the Hakko as you can see a tiny bit of carbon foam on the bottom of this one: https://www.tequipment.net/Hakko/A1586/Fume-Extraction/
Again, this is like $2 worth of material (breakdown), it won't be magic.
the kg no really matter the matter is media filtration material it can have just 1,5kg of this media and can be 100 times more effective than 50kg of activated carbon against most irritant fumes generated while soldering - read my other posts
Not sure what your point is. I was comparing two units with activated carbon, the one with more carbon weight will inevitably last longer.
You can't buy cheap commercial activated alumina systems that I am aware of. Yes it might be worth DIYing your own.
But your claim of 100 times more effective needs a citation. It can be better at some chemicals and worse at others. For formaldehyde its not really significant.
https://www.cwejournal.org/vol6no1/adsorption-of-formaldehyde-on-treated-activated-carbon-and-activated-alumina
in air filters there is one rule - if filter bed isnt enough effective to absorb or chemisorb all needed chemicals then it cant and shouldnt be used because it will going contaminate too fast and refilling costs would exceed costs of second proper filter with correct bed
you have 100 grains of activated carbon and 100 grains of alumina - the 100 grains of alumina will have capacity to chemisorb 10 grams of formaldehyde
the 100 grains of activated carbon would have at last capacity to absorb 0,00001 grams of formaldehyde , the alumina 1kg cost around of 10 euro and 1kg of activated carbon cost 5 euro - where is problem ? the problem is about activated carbon is designed to catch mainly largest particles of gas fumes while impregnated alumina is designed to catch most harder to absorb smallest gas particles
now if you pay 50 euro for 10kg of activated carbon and 100 euro for 10kg of alumina to use for chemisorb/absorb soldering fumes you will pay allways for activated alumina cheaper - why ? because activated alumina will LAST longer than activated carbon ! so in one year if you use alumina you could pay 1000 euro with its refilling but for activated carbon you will pay much more - 5000 euro (this is just example) you pay more for activated carbon because it is not designed for smalles gas particles and you allways contaminate it by these particles faster than activated alumina - now you understand such difference and why commerciall soldering filters uses activated alumina/custom impregnated carbons ? so now if you understand lets explain few other important facts:
at last the 1,5kg of filter bed in solder fume extractor should absorb/chemisorb fumes from small soldering workplace these include spare fluxes - they can create no more than few grams of smallest gas particles during soldering and this filter should absorb/chemisorb 90 - 95% of these particles ! the 1,5kg of standard activated carbon would not absorb you more than 10% of these particles unless you load 150kg of this carbon but you will pay 10 or even 20 times more than specialised alumina for this bed ! so this is not unprofitable to implement and use
now i explain more creep details:
i did make alot of experiments with activated alumina potassium permagnate 8% vs bofa v250 and vs chinese solder fume extractor called knokoo 150w fes150 and heres the result:
diy filter loaded with 10kg of activated alumina mixed with 5kg of activated carbon vs bofa v250 vs chinese fume extractor with just 1,5kg of custom commerciall bed (carbon/alumina) and heres the result
the 1,5kg bofa v250 and chinese fume extractor also 1,5kg of custom filter absorb much more smallest gas particles than my custom diy filter !!! - so where is the point ?!
the point is in bofa and chinese filters custom very-high effective activated carbon/alumina ! it is enough of 1,5kg load to suck most harmfull gas particles but unfortunatelly 10kg of activated alumina with 8% potassium permagnate from CAMFIL isnt enough - they have also 12% for sale but bofa filter bed alumina+carbon and chinese industrial coconut activated carbon are much more effective ! they have very effective filters
in bofa they dont use exactly activated alumina but speciallised industrial activated carbon impregnated by potassium permagnate this is custom and you cant buy it from carbon shop , the chinese fume extractor dont use impregnation on carbon - they use some kind of high-effective coconut activated carbon - industrial grade
usually the impregnation of carbon is used for chemisorb most harder smaller gas particles
you compare one carbon with another carbon filter ? you cant compare this untill you knows whats exactly is inside this filters
also the bofa v250 and chinese fume extractor knokoo fes150 will be not enough to absorb fumes generated from bga station (much more than few grams of gas) - for this you should try fes350 chinese or larger units from bofa because small filters designed for small workplaces
at last in basic reality whorst irritant and harmfull gas particles need very effective gas filters and this filters include very effective carbons/aluminas to meets this requirements otherwise if not all of this filters must be very large and contain alot of bed kgs - so designing diy custom soldering filters are totall waiste of money