It depends on what you mean by storage I suppose. Some the suggestions here seem to assume you mean having all of your filament in cereal boxes with plastic tubing stick out ready to go. While that’s fine for filament in use, it’s not great for long term storage. I have the AMS which is sealed and has a cover with a UV protective coating. I also have a couple (literally two) filament driers that can be printed straight from that also have a UV protective cover on the see through side. That’s it for stuff exposed. The driers I only use to store filament I’m actively drying or using because it can’t go through, or shouldn’t go through, the AMS.
If you’re talking about storing open filament for a few weeks or months because it’s a seldom use item then that’s a whole different consideration. Those cereal box things and the cheap IKEA totes, usually modified with plastic tube outlets to print directly from, are a terrible idea.
Your first consideration is not moisture, it’s UV light. UV light destroys the filament faster than moisture does attacking it at an atomic level and altering its chemistry. Indoor lights should not be overlooked as a source of UV light either. As we have moved away from incandescent light bulbs to LED bulbs many (most?) of those are full spectrum or daylight bulbs which mean they are producing the same wavelengths and light radiation as the sunlight coming in through the window. Light cooks your filament and unlike moisture you can’t even kind of undo that damage.
Moisture and dirt (dust, dander, pet hair, lint, random coffee spills, etc) are obviously your filament’s second and third enemies. Those tubes and holes for tubes that stick out of the the DIY cereal box containers and filament driers let moisture in. If the tube is currently hooked up to a printer it will be extremely minimal and not worth worrying about as the exposed end is going to be having any moisture cooked out by the hot end and then be plugged by solid plastic when it cools.
The DIY containers and filament driers not hooked up however provide a nice pathway for humidity to get at your filament. You can put silica if you like but it’s still pretty much like leaving silica next to the filament on an open shelf.
For filament not in use I store filament in these - https://www.amazon.com/IRIS-Quart-WEATHERTIGHT-Storage-Black/dp/B07R1PSNY5/ref=sr_1_3_sspa?crid=E3FF3F15FZ4U&dib=eyJ2IjoiMSJ9.gTBt5PDcU7Bx9lZ6ukL4vlg7-OVQhQcTI3kNnldFMklDVKlFuM9bBFMH2NPICAhCr8Vp17Vlr8BcpRsSow9Q09EznWxT0E6WVZmlN_MmIVZ0r-kFj8dcRuAabi5-_SQxAGe_g-dIX-z562ylwZE_G2jDAbSqsYhxTDjphhYhPsQGUipFLP6NTuKg_ycKe2K88RH4bNnrjUrSUItd_UoNzyj_7lT0l7NJpBQW1LWgntN8k8mhMkMIe07NX6girsVDjNqi5BzkQR16pBTJ2Na-bTBam1hwkp5NxhWYpVpnitM.ce3Ss8ulWzHYwRiNoD-bFYMNiQY7rfEIoTWMQPcDQN8&dib_tag=se&keywords=weathertight%2Bstorage%2Bcontainers&qid=1715255244&sprefix=weathertight%2Caps%2C69&sr=8-3-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
It doesn’t have to be these but these particular ones are good quality and do all the jobs. They’re black all around so they block light and UV radiation. They have a seal built into the lid and six points of clamping to spread out the clamping force and keep moisture, dirt and dust out. I actually closed one up and sprayed it with a hose outside to see how weatherproof they were and not so much as a drop got in.
To these I added a couple of 3D printed silica boxes about the size of a 4" junction box filled with color changing silica to each bin. I also added temp/humidity gauges to the bins. Just the cheap round ones you can buy half a dozen for under twenty bucks for on Amazon. They take their measurements from air let in on the back side. The round ones are easiest to do deal with.
The bins I linked to, and most bins really, Have a sort of hollow spot. The bins I linked to the hollow spot on the short side in line with the handles. So if you add something there it won’t interfere with being able to put the bins on or under a shelf side by side. For the round ones, I already had one, you can go to the home store and get a hole saw the right size to make a nice neat opening for the gauge. Just get the cheapest brand they have, they’ll all cut plastic equally well for a long time. Don’t use a regular drill bit or large spade bit, you’ll explode the plastic with the forces. The hole saw will cut a nice neat hole. A quick wipe with some sandpaper will get rid of any burr on the plastic. Then you can just pop the gauge into the hole with the display facing out and seal around the outside of it with silicone to make it air and water tight again. Each of those bins will hold 18 to 24 rolls or more depending on the size of the rolls. You can’t fit enough filament in the bins for weight to be a concern.
My filament in those bins has never been above 10% humidity.
