[k3oni]

What i do, is store all spools in a big sealed plastic tote with some bigger desiccant bags(100g). To dry the filament(even if it's new from a sealed bag) i have a smaller plastic tote that will fit 1 spool with a heating pad(like the ones used for your medical purposes) on the bottom. Add the spool and let it sit fro 6-12 hours on top of the heating pad with the lid closed. Pretty cheap heated filament dryer. Here's the heating pad i use, can be found on Amazon for $14: "Boncare® Small Heating Pad Without Auto Shut Off for Cramps and Back Pain Relief"

[Mashimo]

But if the lid is closed, how does the moisture escape? How hot does the air get inside the bag?

[k3oni]

Not that hot, maybe 50-60C, enough to get the moisture out of the filament and into the desiccant while not melting your spool or filament. Was thinking to add a small fan to it one of these days, connected to a battery and on/off switch, but it's working really good as it is.

Just to add to this, i print mostly PETG and PETG-CF, barely any PLA.

[Kirby64]

Moisture gets trapped in desiccant. The hot air drives the moisture out of the filament and into the desiccant.