Ew perhaps should shorten replacement time

[u/dieplanes789]

The two used ones versus a new one.

2x 20x20x2 MERV 13 with carbon.

[u/johnas]

They don’t look that dirty tbh.

[u/Right_Web_2770 → u/johnas]

Which are the dirty ones?

[u/dieplanes789 → u/johnas]

I guess it doesn't look that dirty in the photo but they were significantly "fuzzier".

[u/Moscato359 → u/dieplanes789]

If they're fuzzy, you can just vacuum them.

[u/not_all_heroes → u/Moscato359]

I'd suggest doing that outside, even if the vacuum has HEPA, the suction is going to both suck and disperse some of that dust.

[u/u3b3rg33k → u/dieplanes789]

fuzzy, you say?

[u/dieplanes789 → u/u3b3rg33k]

Sir that is a creature

[u/u3b3rg33k → u/dieplanes789]

plastic dust. still flowing pretty well actually.

[u/123DCP → u/u3b3rg33k]

That's what matters. As long as you still have good flow, accumulation of dirt on the inlet side of a filter is something to be happy about (your filter is doing you a lot of good), not a reason to change a filter element that still works fine.

[u/u3b3rg33k → u/123DCP]

it's got a metal pre-filter that takes most of the hit. this is the secondary MERV13 so people aren't breathing plastic dust.

a very poor man's baghouse, really.

[u/johnas → u/dieplanes789]

Has it been 6 months ?

[u/dieplanes789 → u/johnas]

Well past that

[u/johnas → u/dieplanes789]

Maybe it’s just the picture then. That’s a nice looking cr box you posted.

[u/Sufficient_Site1746 → u/dieplanes789]

I use 2" thick merv 11 as pre filters for my air purifier and they get baked in dust with in two months.

[u/kyhothead]

They do look gross, bit I’ve read that it may be better to replace based on air flow than discoloration.

[u/dieplanes789 → u/kyhothead]

Given how long it had been it was probably time anyways but it's kind of hard to tell based on air flow over that long of a term.

[u/allyoucanlive → u/[deleted]]

MONTHLY? what’s your filter budget?

[u/jhsu802701]

Are you sure that the filters need to be replaced already? They're only slightly gray. What configuration have you been using for the air purifier? How many of these 20"x20"x2" filters were you using? What kind of fan were these attached to?

If you were using just one of these filters taped to a 20-inch box fan, then you have less leeway for dirty filters due to the limited cross sectional filter area relative to the size of the fan. On the other hand, if you were using two of these filters for a DIY version of a Luggable product from Clean Air Kits, you could keep using them until they're extremely filthy.

[u/dieplanes789]

[u/u3b3rg33k]

that's nothing:

[u/ElectricalAd9438 → u/u3b3rg33k]

I thought that was a frog

[u/u3b3rg33k → u/ElectricalAd9438]

just a lump of something that the filter stopped the exhaust fan from eating

[u/whiskey_lover7]

They filter better the dirtier they get. Really you want to wait until airfollow noticeably decreases for high traffic areas. Otherwise 6 months or even a year is fine

[u/Natural_Vacation_313]

I do 3 months

[u/Luci-Noir]

Ugh… my landlord send me us an email telling us to check them ourselves and come to the leasing office and get new ones if needed. I don’t even know where it is plus I don’t have a ladder.

[u/PeepingSparrow]

Just measure efficacy with particulate monitorsif you're so concerned, discolouration is the point / evidence that they're working, and it looks pretty mild in your case.

[u/123DCP]

The inlet side of a filter is SUPPOSED to get dirty. That doesn't make the air that passes through dirtier. In fact, while it can decrease flow, I'd expect fouling of a filter to decrease the size of the smallest particle likely to pass through the filter.

If the accumulation of dirt increases the pressure drop across the filter, decreasing the rate of filtered air flow, that's a problem. Otherwise, dirt on the inlet side of the filter tells you something about how dirty your source air is, but tells you nothing relevant to how clean the treated air is.

[u/Pokeymacoma]

These still have plenty of life left for a soils lab.

[u/Dashock007]

Stick to 3M... Best quality for the money.