Cultivation supplies
by Microppose
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The Microppose Adherable Monotub Filters are a 12-pack of self-adhesive air exchange filters designed for the Microppose Monotub grow chamber. Each filter measures just over 2 inches (roughly 5 cm) in diameter, covers the tub's pre-drilled holes precisely, and lets fresh air flow in while locking humidity inside and keeping bacterial and fungal contaminants outside. Made from 100% recycled filter material with a durable 3M adhesive backing, they stick on in seconds and stay put flush after flush.
| Spec | Value |
|---|---|
| Brand | Microppose |
| Quantity | 12 filters per pack |
| Filter diameter | Just over 2" (~5 cm) |
| Material | 100% recycled filter media |
| Adhesive | 3M self-adhesive backing |
| Designed for | Microppose Monotub |
| Primary use | Fruiting-stage air exchange |
| SKU | SH0195 |
Running a Microppose Monotub? These filters are only half the equation. Pair them with the Microppose Monotub itself for a matched setup, or grab the Adherable Injection Ports 50-Pack if you're inoculating your own substrate bags and want clean, self-healing entry points.
Mushroom mycelium needs gas exchange to fruit properly — carbon dioxide builds up inside a sealed tub, and without fresh air replacing it, your pins stall or never form at all. The obvious fix is to drill holes in your monotub. The less obvious problem: every open hole is an invitation for contaminants. Bread mould, Trichoderma, Bacillus, cobweb mould (Hypomyces rosellus) — any of these can colonise your substrate faster than your mycelium can, and once contamination takes hold, the batch is usually done for.
We've seen growers lose entire flushes to a single unfiltered hole. It's genuinely painful to watch three weeks of patience get wiped out by green Trichoderma creeping across the surface. These Microppose filters sit over each hole and act as a physical barrier: air molecules pass through, spores and bacteria don't. The recycled filter material has a slightly rough, papery texture — not as stiff as polyfill, not as flimsy as micropore tape. It feels like it'll actually last, and the 3M adhesive confirms that. Once pressed on, it doesn't peel at the corners the way tape tends to after a few days of humidity.
The honest limitation: no filter replaces proper sterile technique. If you're reaching into the tub with unwashed hands or opening the lid in a dusty room, contamination will find a way in regardless. These filters handle passive air exchange through the side holes — they don't sterilise your workflow. Think of them as one layer in a clean setup, not a magic shield.
The number one question we get about monotub growing is "how much air exchange do I actually need?" The short answer: during colonisation, very little — you want CO2 to build up slightly, which encourages mycelial growth. During fruiting, you want significantly more FAE to trigger pinning and prevent fuzzy feet (aerial mycelium reaching upward because the mushrooms are gasping for oxygen). That's exactly the stage where these filters earn their keep. They provide consistent, passive airflow without you having to crack the lid every few hours.
One thing we'd flag: if you're growing in a particularly warm or dry environment (above 24°C or below 80% relative humidity inside the tub), even filtered holes can let too much moisture escape. In that case, covering one or two of the filtered holes with a piece of tape during the first few days of fruiting can help you dial in humidity. The beauty of having 12 filters is that you can experiment — try 4 open, try 6, see what your specific strain and environment prefer. We'd start with 4 on the long sides of the tub and adjust from there.
The Microppose Adherable Monotub Filters are specifically designed to block common mushroom cultivation contaminants. Here's what you're defending against:
| Contaminant | What it looks like | Why it's a problem |
|---|---|---|
| Bread mould (Rhizopus/Mucor) | Grey-black fuzzy patches | Spreads rapidly, smothers mycelium |
| Trichoderma | Bright green spots or patches | Aggressively outcompetes mushroom mycelium |
| Bacillus (bacterial) | Slimy wet spots, sour smell | Breaks down substrate, produces off-odours |
| Cobweb mould (Hypomyces rosellus) | Wispy grey overlay | Covers pins and fruits, ruins the harvest |
Filtered air exchange won't eliminate risk entirely — substrate preparation, spawn quality, and your own hygiene practices all play a role — but it removes one of the most common contamination vectors: airborne spores drifting through open holes.
They're sized at just over 2 inches to match the Microppose Monotub's holes specifically. If you've drilled your own holes in a different tub and they're roughly 2" or smaller, the adhesive ring will cover them. Anything larger and you'll get gaps around the edges.
Replace them between each grow cycle. After 3–4 weeks of exposure to high humidity, the filter material can become saturated or start to degrade. At 12 per pack, you've got enough for at least two full tub setups or one tub with spares for a mid-grow swap.
No. The 3M adhesive is single-use — once peeled off, it won't re-stick reliably. And washing the filter material risks compromising its pore structure, which defeats the purpose. Fresh filters are the way to go.
They're more consistent than both. Micropore tape loses adhesion in humid environments within days, and polyfill is fiddly to get the density right — too loose and contaminants slip through, too tight and you choke airflow. These filters are purpose-built for monotub growing and the 3M adhesive actually holds in high humidity. That said, micropore tape works in a pinch if you're on a tight budget.
They block airborne contaminants from entering through the tub's holes, which is one of the main contamination routes. They won't protect against contamination already present in your substrate, spawn, or introduced by handling. Always sanitise your hands, tools, and workspace before touching anything inside the tub.
Use them during both stages. During colonisation, they allow minimal gas exchange while keeping contaminants out. During fruiting, when you need more FAE, the same filters let a steady flow of fresh air in. Some growers tape over a few filtered holes during colonisation and remove the tape for fruiting — that works well.
100% recycled filter media. Microppose doesn't disclose the exact polymer composition, but the material is non-woven, breathable, and rated to block bacterial and fungal spores while allowing air exchange. It has a slightly textured, papery feel — sturdy enough to hold up in a humid monotub environment.
Last updated: April 2026
Medical disclaimer. This content is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before use of any substance.
