How are you drying your air? I’m familiar with air dryers because we had them where I worked but I have never seen an affordable hobby level device myself.
We had 4 sets, each set had two desiccant towers that were about 12’ tall and 4’ in diameter and had an electronically controlled dry/regeneration cycle that would swap the towers.
I’ll leave the preppers to their own devices.
We had one of those cats put a bunker in his back yard not far from where I used to live. He did it going into Y2K and I wonder to this day when he cracked the hatch on that thing on Jan 1, 2000 and earth wasn’t an apocalyptic wasteland.
I’m using 2.5" refillable filters in 10" water filters. I’d prefer 4", but the only refillables I’ve found for those are opaque, whereas I found some 2.5" refllables that are transparent, so that I can see the desiccant gel indicator color through the transparent housing.
That said, one can string them in series to get whatever capacity you want.
You can buy the refillable cartridges on amazon, but they’re far cheaper on aliexpress.
Or, you can DIY an equivalent solution, like this guy did using a water bottle:
Once you catch the idea, you start to see how easy it is. You could even use gallon size mason jars if you wanted to, and with that you’d get both huge capacity and the transparency.
The absolute ultimate would be a tandem switching architecture, as you allude to, but where it also automatically dries the used desiccant cylinder after switching to the fresh one. Those exist in industry, but maybe overly complicated for a DIY build.
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I think you built what I started to build then just quit with.
You can buy these on Amazon
SimPure Whole Home Water Filter housing (DB10C), 10" x 4.5"
Yes, exactly so, but with a refillable cartridge to make swapping out the old desiccant and in the new desiccant super easy and fast:
It obviously wasn’t designed for desiccant per se, but instead water softener beads or activated charcoal or the like. But water-tight is good enough for air-tight in this application, because the pressures involved are so low. Even 1psi above barometric air pressure is good enough, because you don’t require a high flow to do the job. In fact, too high a flow and you’re just wasting the dry air you generate.
I made a solid walled drop tube with a basket strainer with mesh smaller than desiccant so air had to go from top to bottom then out to to AMS. I do not keep a very big inventory of filament so figured to purge the AMS devices. I subscribe to the dewpoint of water keeps filament dry in the manufacturers vacuum sealed bags until it goes in the AMS
That’s essentially what the makerworld design does too, and he seems very happy with his water bottle solution. He uses a straw as the droptube.
I’m not sure what you’re saying in this sentence.
For the 1 gallon mason jar solution, I would use a bulkhead quick conector to aquarium tubing, terminated by an airstone, as my “droptube” to the bottom. I haven’t built it yet, but seems like it couldn’t fail. Then just another bulkhead connector to skim air from the top as the outport port. No mesh required. Gravity alone should be enough to keep the desiccant out of the exit port. Being a mason jar, the lid will seal airtight.
Also, being glass, there will be zero moisture penetration into the container from the environnment. Therefore, add a couple ball valves at the top for both the input and output ports, and you can shut it off completely if you want to store it unused for any length of time, all while keeping the desiccant perfectly fresh.
To finish it off, I would 3D print some kind of protective crate around the 1 gallon mason jar out of TPU or something, as added protection against the glass breaking from an accidental impact. Not strictly needed, but I believe in Murphy’s Law.
If this kind of thing interests you, consider joining one of the threads where a bunch of us have brainstormed this topic. The more the merrier! Bring some fresh ideas. Probably best to do that and allow this thread to continue as before.
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If you have a decent vacuum, all the water has boiled off. so the when they pull the vacuum on the bag prior the water would have boiled off. As long as the bag is still under a vacuum, it is still dry.
I think the filament is like milk. It is going to spoil at some point, no matter what you do. So I try and keep my filament new. I’m not overly concerned with color and I buy just BL filament because it has proven to always be dry when I buy it. YMMV
If BL would sell filament on Amazon it would be great because I can generally get second day delivery and I could buy color/material as needed.
I see these vast stacks of filament that people will post and I just see that as $$
Provably false. I’ve lost count of the number of freshly delivered spools of filament, still under “vacuum”, that I then dried more than 10g of moisture off of.
You would be correct if it were an absolutely hard vacuum. But that’s not what you’re getting. If there’s moisture in your filament, then even if it was an absolute vacuum at the begining (which I’m sure it wasn’t), it can still stabilize at around 220 microns, which is still a strong vacuum, even while there’s plenty of moisture remaining in your filament.
Don’t take my word for it. Try it yourself and you’ll quickly see.
That is why I qualified my statement with it being BL filament only and in my experience. Your experience with BL filament may be different. I have gotten other brands of filament that are the bag is deformed but the vacuum is gone. When I first snip a BL pouch I can hear it pull in air.
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Well, then, why does Bambu recommend drying PPS-CF, even fresh out of the vacuum bag?
I’ve already done the experiment, and all I can do is suggest you do as well.
Good luck!
I use the clear cereal containers from Amazon with some desiccant in them.
It was also my finding too - “measuring” filament moisture indirectly like this absolutely works and works well. All you need are good go/no go values. If a spool is too high moisture content, dry it some more before using until it passes. It’s trivial to do and should be very reliable.
I’ve only done it a few times but it has worked great. What I do instead is dry my spools to 19% RH hot in the dryer and then put them in thick-walled cereal poly containers with a sachet of silica gel beads and a hygrometer. All my spools pull below what the hygrometers can read - 10% - when they cool to room temperature. I have a few that have leaked up and they will get dried again before use, but if the hygrometer is reading 10% at room temperature then I know the filament is ready to go and any issues won’t be water.
It’s just my procedure now and has been 100% reliable for water effects. I’ve been doing this for a year and a half now and it just works.
And NeverDie cited my air dryer above. It’s more complicated than it needs to be but the basic principle works. All you need is a tube or bottle of some kind (do not appreciably pressurize glass - explosion hazard) and a tube to make air enter at top or bottom and exit at the other end. Longer and narrower is better than short and squat to give humidity plenty of residence time to be desiccated out. The air coming out of mine is lower than a single percent RH as best as the hygrometer I used could measure it.
During drying, I start heat in my dryer and prop the door open about a half centimeter (Sunlu S2+) and let it cook while the main water comes off. The dryer RH spikes up and then starts falling as the main water leaves. When that fall starts slowing is when I turn on the dry air purge. By time it’s 4-5 hours into the dry. In another 4-5 hours the RH in the dryer will have dropped to 19% (or below with a fresh column) and that’s when I pull the spool out to put into storage or an AMS. As it cools it pegs the storage hygrometer at 10% and it’s good for months. I’ve still got spools I dried over a year ago showing 10% RH in storage.
I use indicating silica gel (the orange non-toxic kind) in the drying column and it’s still interesting watching as it captures water. I add the ambient air at the bottom and the dark green starts at the bottom and gradually moves up during use. With my ambient humidity I can dry about 40-50 spools before the whole column turns green. And time to 19% RH gets longer as the column gets used up. It is the same thing as trying to dry in more humid environments. It gets harder/slower to dry filament as the humidity increases so I just regenerate the beads and get back to business. (As an aside, I’ve since learned the humid air should enter at the top. It’s less dense than dry air so tends to rise. H2O vs O2 and N2. Water vapor is lighter so will float up like a hot air balloon - but this doesn’t seem to affect my column lifetimes much that I notice.)
I’ve refined the procedure a bit. Instead of always blowing dry air into the filament dryer I switched to the door prop for the first half of the dry which makes the beads last about twice as long. The beads get used up depending on purge rate and ambient humidity with this setup. The 25 spools number in the photo was using dry air the entire dry.
And all this needs the disclaimer that it’s probably not necessary for everyone. Others with systems that get them dry filament don’t need this kind of thing. But I did need it and it has been the best upgrade I’ve made to my own 3d printing. I had water effects start showing up shortly after I got my printer as ambient humidities rose and had to do something as my prints were getting bad - unacceptably bad.
With dry filament I haven’t had to calibrate anything on my printer other than the initial automated calibration. All the filament settings are stock and I get great prints. Other’s mileage will certainly vary.
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And for maintaining dryness inside an AMS 2 Pro, after whatever drying method, I’ve found these well crafted printed containers for putting more desiccant inside the AMS help quite a lot:
Doing that the AMS 2 Pro will initially report 0%RH, and over a period of days you can watch the reported RH% creep up, reflecting ongoing moisture penetration from the outside. It just creeps up more slowly with the pods than without them, so it buys you extra time before you have to do something about it. A lot of people like to keep filament at-the-ready in their AMS so that they can fire-off a print at the drop-of-a-hat whenever they want.
Pumping in dry air would buy even more time. Indefinitely long, until you need to replace the desiccant in your dry air emitting desiccant column with fresh. I’ve done that on the AMS HT and other standy-by-to-print filament dry boxes to good effect. It definitely works.
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Costco stores in various areas and even within the same city will stock different products. I know this as I have two Costco stores 10 miles apart with one in a more pricey part of town (Cincinnati burbs) and you’ll find different inventories even though the stores are the same size.
Did you have any problem getting the larger pods to fit? The side pods went in no probelm, but I cannot get the larger pods to fit? Did you have to scale them down to fit? I printed them as is.
Reporting back: Some of you may remember that earlier in the thread this IP-67 container carried at Home Depot generated a lot of interest:
because as a drybox it was (and is) a good size to store 4 rolls of filament.
Well, good news! Walmart now carries two series of IP68 (note the upgrade over the former IP67 rating) containers. One is by Sterilite, and the other one is named Bunker, made by ez-storage, the same manufacturer as the IP67series at Home Depot).
Worthy of note is that the Sterilite series is a lot less expensive. That said, the wall thickness appears to be different in the different linups. I measured the wall thickness of the lids, since that affords the easiest access for calipers. The Sterilite measured about 1.8mm, the ez-storage from Home Depot measured about 2mm, and the Bunker measured about 2.3mm. The Sterilite and the Home Depot ez-storage seem to be made from roughly the same type of plastic (maybe PP?) whereas the Bunker series seems to be different (according to the description, the lid is polycarbonate). There were no recycle numbers that I can could see, so I can’t be sure, but, in addition to wall thickness, it might have an effect on the moisture transmission rate into the different containers.
Lowes now carries IP68 containers in its Kobalt line. On its face it looks very similar to the Bunker Tough, but more expensive:
This thread has been dormant for a while. Anyone discovered any other good finds?
I’m fond of Home Depot’s “Husky” branded 20 gallon waterproof bins, which easily hold a dozen spools:
They’re very, very rugged and seal extremely well. Looks like they’re currently on sale for $30 (normally $36, and before the market madness of 2025 they were $28).
It looks as though it’s an earlier generation. I couldn’t find an IP rating on the 20 gallon, but according to the home depot website, the 5 gallon is IP65:
so maybe (?) the same is true for the 20 gallon that you like that’s on sale for $30 (normally $36)
For future purchases, if any, I’d suggest upgrading to the Bunker Tough 20 gallon, as it’s IP68 rated and only $25 regular price:
Like the Husky the lid is polycarbonate, and inferring from the Husky description above, very likely the rest of the body is a “durable polypropylene.” 
That said, the listing has it at 19.8 gallons, and exact dimensions might be different, so check in detail before pulling the trigger as to whether it still matches your requirements. For instance, I had thought the 5 gallon bunker tough was going to be exactly the same size as the prior 5 gallon ez-solutions (from Home Depot), but the Bunker Tough actually seems to be quite a bit larger with more volume, so there may be quite a lot of rounding error in the listed product specs for these things.
I hope this doesn’t come across as pedantic. Just trying to share the benefits of what “hands-on” data I’ve managed to scrounge, as well as hopefully help re-ignite this smoldering thread and hear updates from others too. Collectively we’ve had a lot of good postings in the past, but need to keep it current with updates. Hope it helps!
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Some good points there!
I wouldn’t worry much about the IP rating for this purpose, as it is about mechanical resistance to water pressure. IP 65 is meant to withstand low pressure jets of water, aka heavy rainstorms. IP 68 handles submersion.
I’ve left power tools outdoors in the rain for days in the ip65 Husky bin with no issues. It’s more than adequate for filament storage.
Those Walmart ones have an undeniable edge in price though… I find that pretty compelling!
Oh! Also, yes, the husky bin is polypropylene, just the lid is polycarbonate.