Monotub Liner 10-Pack (Microppose)

Monotub Liners for Microppose Tubs — Keep Your Grow Clean, Ditch the Scrubbing

The Microppose Monotub Liner is a custom-fitted polyethylene bag designed to line the inside of your Microppose Monotub, protecting the tub from substrate residue and making end-of-cycle cleanup a 30-second job. Sold in packs of 10, available in three sizes (Small, Medium, and Large) to match the full Microppose Monotub range.

Why You Actually Need Monotub Liners

Here's the honest version: you can grow mushrooms in a monotub without a liner. People do it all the time. But after your first harvest, when you're chipping dried substrate off the walls with a spatula and wondering if that discolouration is contamination or just staining — that's when you'll wish you'd spent a couple of quid on a liner.

The practical problem is straightforward. As your mycelium colonises the substrate and begins fruiting, the substrate block shrinks. It pulls away from the tub walls, creating a gap. That gap is a microclimate — humid, dark, sheltered — and it's where side pins love to form. Side pins are mushrooms that fruit along the bottom and sides of your cake instead of the top surface. They're awkward to harvest, they waste energy that could go into your main canopy, and they make the whole operation messier than it needs to be.

A liner solves this because the thin plastic clings to the substrate as it contracts. No gap forms, no microclimate develops, and your pins concentrate on the top surface where you actually want them. It's not a magic trick — it's just physics. The liner also means your tub stays clean between grows. Pull out the liner, wrap up the spent cake, bin it, and your Microppose Monotub is ready for the next round without scrubbing. We've seen growers get years of use out of a single tub this way, versus the ones who go liner-free and end up with stained, scratched plastic that gets harder to sanitise with every cycle.

What Makes These Liners Worth It Over DIY Alternatives

We'll be straight with you — some growers just cut bin bags to size and call it a day. It works, sort of. But bin bags aren't sized to your tub, so you end up with excess material bunching in the corners, creating folds where water pools and contaminants hide. You also spend 10 minutes per tub faffing about with scissors and tape when you could be inoculating.

The Microppose liners are pre-cut to the exact internal dimensions of each Microppose Monotub size. They sit flat against the base and walls with enough extra length at the top to fold over your spent cake when it's time to dispose. The plastic is thin enough to cling to contracting substrate but thick enough that you won't accidentally puncture it during spawning. It's a small detail, but when you're running 4 or 5 tubs at once, the time saved and the consistency gained adds up fast. Ten liners per pack means you've got enough for 10 full grow cycles — or 10 tubs running simultaneously if you're scaling up.

How to Use Microppose Monotub Liners

1. Sanitise everything before you start. Wipe down your Microppose Monotub with isopropyl alcohol (70% concentration works well). Then sanitise the liner itself — lay it flat and wipe both sides. Ungloved hands are how entire batches get lost to contamination.
2. Open the liner and place it inside your monotub. Press it gently into the corners and along the base so it sits flush against the walls. Let the excess material drape over the top edges of the tub for now.
3. Add your substrate and spawn mix on top of the liner as you normally would. Spread it evenly across the base to your preferred depth — typically 7–10 cm for most cubensis grows.
4. As colonisation progresses and the substrate shrinks, the liner will contract with it. You don't need to adjust anything — just let it do its thing.
5. After your final flush, when the cake stops producing, open the tub and fold the excess liner material over the top of the spent cake. Lift the whole package out in one go and dispose of it. Your tub underneath should be virtually spotless.
6. Give the tub a quick wipe with isopropyl alcohol, drop in a fresh liner, and you're ready for the next grow cycle.