This was supposed to be written on the same day as Log1 but I didn't have the time. At least I can now also talk about the specific filtration system I ended up buying.

Research into carbon filters in general

So I started some research and it was suggested to get a carbon filter that had at least one full air chainge per minute. 

2.4 x 1.2 x 2 = 5.76 m^3 => 203 ft^3

 There's loads of fan efficiency debuffs along the way though, so my aim was 350 CFM (cubic feet/minute)

I thought that a human would require more ventilation than small plants, but it seems that the actual requirements are much lower:

That area entered in is on overestimate too. 

From my research, quite a few sources say that a carbon filter should be good for a year minimum. It is also straightforward to stretch this longevity to 2 years.

I'm skeptical because I have a small air purifier that claims 6 months filter life, but the filters were spent within 4 weeks. However, I was researching the Nevermore when researching for the #SecSavr Suspense [gd0105] and these kinds of consumer air purifiers likely don't have enough activated carbon / charcoal to last very long. 

Still though, spending (as I'd soon find out) £40 - £50 on a massive filter that lasted 6 months is still better than 1 small filter / month costing >£9 that likely only effectively filters for half the time. Also note that those 1 - 2 year expectations are with the filter running 24/7 and I wasn't running my small purifier 24/7.

Researching purchaseable options

The first filter I found was from Vivosun because I had just found thier £120 tent and wanted to see what else they had.

These kinds of things really do look cool.

I find this listing and am suprised that you get all this for only £53:

The 6" wasn't in stock when I first saw this listing, but it was the next day for £65.

Anyway, I eventually found and added the red-blade fan kit into my basket. The 300mm long filter was only £9 less and I thought that a longer filter would last longer and allow more airflow. Looking though the seller's store, I found the same listing but with a white-blade fan. The listings don't really talk about the fan in enough detail to pick on over the other, so I went with the white one because it looked better and a bit longer.

The reason why I went for the £82 kit instead of the £65 kit is because I did some looking around on filter / fan prices and that £65 was a bit suspicious. The cheapest 150 x 500mm filter was £40 and the cheapest 6" fan (the red-blade one) was £41. I looked into the filters each kit seller sold as individual listings (because they probably don't stock filters specifically for a kit and a different filter for refils) and the £65 seller never mentioned anything about "Australian Mined RC412 activated carbon". I've seen that specific carbon mentioned on so many listings that I thought it was redundant or just an industry standard. Lastly, the £65 kit only did 150 x 300mm (which is acceptable for the price difference).

I also found out about fan speed controllers:

So if the 6" fan is too loud (which is my main concern over choosing a 5" fan), i could potentially use this to tone it down.

Trying the system

So it came in a massive box to the right (and the broken LCDs are in the box to the left, which I'll talk about in the next log)

Here's the fan. Note how it says 33dB at 3m distance. I think the red-blade  fan was rated at 46dB at 1.5m, so I perhaps this fan would be something like 43dB at the same distance? (This is assuming that halving the distance doubles the apparent sound, which is equivalent to 10dB).

Just woughe. That entire carbon filter is like 2X the entire air purifier in size. Perhaps this thing really could actually last. It also came with a black pre-filter (which is unusual since they're usually white) and some tiny black particles which are visible on the table if you look closely (possibly the activated carbon).

Tested the fan. Sounded kinda loud but ok, like a peaceful vacuum cleaner. Then I stacked the fan ontop so that it blew upwards. Perhaps 5 - 7 minutes into this, I decided to see what the dB reading is. I'd imagine it'll be quieter with the ducting on, but I measured 53dB at around 2m. I stood closer to get more data and, moments later [strange ominout sound] was emmitted from the fan and the airflow and noise level dropped substantially. I assume this is a fault so I turn off the fan.

I didn't see anything fall into the fan and I didn't see something like a loose bit of activated carbon inside that could've been whisked into the system. It's also on a surge-protected socket which hopefully prevents any strange spikes from damaging equipment.

I was hoping to at least get a room purifier going, since this setup should be able to change the volume of air in my entire room over 10 times an hour. Unfortunately the indifferent universe said NOPE to my hopes.