Really confused right now.

From my testing, I'm finding out that the bleached white filters have a much slower draw rate than the unbleached brown filters.

Same coffee, same grind, same temp - when I make coffee at home using the exact same technique using unbleached filters, my pour-over finishes at about 2:45 - 3:30. Cup comes out glorious and awesome.

At work, same coffee, same grind, same temp - using bleached white filters, my pour-over finishes at around 3:30-4:30, sometimes I even have to lift the filter a bit to speed it up. Cup comes out over-extracted and muted.

Only difference is I'm using bleached filters instead of unbleached, and that I rinse the unbleached filters with RO water instead of filtered water at work. Both coffees use around 170-180ppm water.

Anyone else experience something like this?

I am. I haven't done any work to identify if the filter is indeed the problem, but I've definitely noticed a slower draw. It seems to have happened after I switched to the bleached Chemex filters.

Exact same grind (i.e. grinder and particle distribution) at work too?

Exactly the same. Ground from home, and brewed an hour later at work.

Not exactly the same! Degassed grounds are your answer, not filter color.

That's my thought as well. Bring some of those filters home, try it with freshly ground coffee and see if the drawdown is the same. I bet you'll find the difference disappears.

If the weave of the unbleached papers is tighter, it may not be suffering from clogging by small particles as much as the bleached paper?

Interesting. I'll give it a shot. As soon as I grind them, I do put them in an air tight container and I still see the coffee grounds degass/bubble during my pours.

More tests and my results indicate that the bleached filters have a tendency to clog/draw slower much more often.

I tested this both at home, using 30g/480mL, same coffees. Aiming for 3min - 3:30min draw, with all of my water poured by the 2 minute mark, with pours at 00, 30, 130. Non-bleached filters consistently finished around 2:50 - 3:20. Bleached filters always seemed to go over by at least a minute (4min+), and in many cases, I had to "assist" it by lifting up the filter. Grind is 7F on a Baratza Forte BG.

Not looking good for these bleached filters, for me anyway.

Grind coarser for the bleached filters and change your pour regime when using the faster draining non-bleached filters (break it up into smaller pulses, but to this methodically).

Though a 4:00 total brew time isn't necessarily a problem in itself.