Complete Refill Kit for Large 66Q Monotub - Includes Grain Spawn & Bulk Substrate
$5999Unit price /Unavailable-
Complete Refill Kit for Medium 44Q Monotub - Includes Grain Spawn & Bulk Substrate
$3799Unit price /Unavailable 
$16.00 offMycoClimate Medium 44Q Monotub Automation Upgrade Kit
$6399$7999Unit price /Unavailable-
$15.00 off
MycoClimate Large 66Q Monotub Automation Upgrade Kit
$7499$8999Unit price /Unavailable
Which Monotub Refill Do You Need?
Your monotub is reusable — what gets used up each grow is the grain spawn and bulk substrate. A refill kit replaces exactly that, matched to your tub size, so you can run the next flush without measuring or sourcing components separately. Match the refill to the tub you already own:
| Refill | Fits | What’s included |
|---|---|---|
| Complete Refill — Medium 44Q | 44Q monotub | Grain spawn + pasteurized bulk substrate, sized for a 44Q tub |
| Complete Refill — Large 66Q | 66Q monotub | Grain spawn + pasteurized bulk substrate, sized for a 66Q tub |
| Grass Lover’s Specialty Refill | XL Grass Lover’s kit | Substrate + casing mix for the specialty grass-based grow |
| MycoClimate Upgrade (44Q / 66Q) | Matching 44Q or 66Q tub | Automation hardware that adds hands-off climate control to your tub |
Prefer to Source Components Yourself?
Refill kits bundle the right spawn-to-substrate ratio for convenience, but you can always buy the pieces on their own:
Monotub Refill FAQ
What is a monotub refill kit?
It’s the grain spawn and bulk substrate needed to run another grow in a monotub you already own, bundled at the right ratio and sized to your tub. Your tub, lid, and liners are reusable — the refill just replaces the consumables that get used up each flush.
What size refill do I need?
Match it to your tub: the Medium 44Q and Large 66Q refills are sized for those tubs. If you run the XL Grass Lover’s specialty kit, use its dedicated substrate & casing refill instead.
How many times can I reuse a monotub?
The tub itself can be reused many times as long as it’s cleaned and sanitized between grows. What you replace each cycle is the spawn and substrate — which is exactly what these refill kits provide.
Can I buy spawn and substrate separately instead of a refill kit?
Yes. The refill kits exist for convenience — the right amounts at the right ratio in one order — but you can buy grain spawn and bulk substrate on their own if you prefer to mix your own.
What does the MycoClimate automation upgrade do?
It adds automated climate control to your 44Q or 66Q monotub, helping hold steady humidity and fresh-air conditions so your grow is more hands-off and consistent. It’s an upgrade to your existing tub, not a consumable refill.