The MycoClimate™ Automated Monotub takes the two variables that wreck most bulk grows — temperature swings and stale air — and puts them on autopilot. A submerged aquarium heater with a built-in digital controller holds the chamber steady from a water bath below, and a timed air pump feeds gentle fresh air through a diffuser stone. This guide walks the whole cycle: water bath, lid, air system, incubation, spawning to bulk, lighting, fruiting, harvest, and cleanup.
New to bulk growing? Read the spawn bag & grain jar guide first — it covers sterile inoculation and getting your grain spawn started, which happens before anything on this page. The rest of our library lives at midwestgrowkits.com/guides.
The whole grow at a glance
- 74–76°FColonization air temp
- 72–75°FFruiting air temp
- 10–21 daysColonization
- 4–7 daysPins to harvest
- 2–4Flushes
- 12–16 hrsLight per day
| Stage | How long | What's happening |
|---|---|---|
| Grain spawn incubation | Varies by species | Bags colonize in the warm chamber before anything goes in the tub |
| Bulk colonization | 10–21 days | Lid closed, surface gradually turns white |
| Pinning | Begins at full colonization | Increase air, add light, small pins appear |
| Fruiting | 4–7 days after pins | Mushrooms size up rapidly |
| Next flush | 5–10 days after harvest | 2–4 flushes total, each a little smaller |
Step 1: Fill the water bath and set the heater
The MycoClimate heats your grow indirectly. The heater sits in a water bath in the lower tub, and that warm water holds the chamber above it at a steady temperature no matter what your room does. This is why it works in a cold basement or a garage where a bare monotub would stall.
- Install the suction cups on the back of the aquarium heater.
- Add clean tap water to the bottom black tub. For the 44Q system, roughly 2.5–2.75 gallons. For the 66Q, roughly 3.1–3.25 gallons. Either way you are aiming for about 4 inches of depth — enough to keep the heater fully submerged while the two bases sit stable.
- Place the heater in the center of the tub and submerge it completely.
- Plug it in. The display lights up and shows the current water temperature.
- Set your temperature. Each press of the button raises the setting by one degree, cycling through the range.
Heater settings by room temperature
| Your room temperature | Set the heater to |
|---|---|
| Below 60°F | 78–80°F |
| 60–70°F | 76–78°F |
| 70–74°F | 75–76°F |
Why the heater number is higher than your target: the heater setting is the temperature of the water, not the air inside your monotub. Heat has to cross from the bath into the chamber, so the water always runs a few degrees warmer than the air you are actually trying to hit. Your target is 74–76°F inside the tub — that is what the thermometer tells you, and that is the number to trust. Colder rooms lose more heat through the walls, which is why they need a higher water setting.
The bath warms gradually and can take several hours to come up to temperature. Stirring the water gently helps it distribute faster. Once it is at temperature, set the second base tub on top.
Step 2: Prepare the lid
- Snap the four black plugs into the side holes of the lid — two on each side.
- Peel and stick the filter disk onto one end of the lid.
- Install the plug with the small hole into the opposite end. This is where the air line will pass through.
During incubation, set the round thermometer/hygrometer inside the bottom of the tub so you can read the internal temperature. If the internal reading climbs above 76°F, drop the heater setting by a degree or two. Light is not needed at this stage — a dark spot is fine, and ordinary indirect room light causes no problems.
Step 3: Connect the fresh air system
The air pump is what replaces the daily fanning a manual monotub needs. Short bursts of fresh air throughout the day keep carbon dioxide from building up, without the humidity crash you get from opening the lid.
- Gather the parts: air pump, blue tubing, diffuser stone, and the plug with the center hole.
- Run the tubing through the plug in the monotub lid so it extends toward the center of the chamber.
- Attach the diffuser stone to the end of the tubing inside the tub.
- Connect the other end to the air pump, and set the pump outside the tub on a flat surface.
The diffuser stone matters more than it looks. It slows the incoming air and spreads it in several directions, so you get slow, gentle movement through the chamber instead of a jet of air blowing onto one spot of substrate and drying it out.
Air pump timer settings
Run the pump through the included 24-hour timer. Each notch on the dial is 30 minutes.
| Stage | Pump ON | How often |
|---|---|---|
| Incubation | 30 minutes | Every 8 hours |
| Early fruiting | 30 minutes | Every 2 hours |
| Heavy fruiting | Continuous | Leave it running |
These are starting points, not rules. A well-ventilated room can take slightly less; heavy condensation inside the tub means you should add more.
Extra airflow once pinning starts
When mushrooms begin to pin, the chamber wants more air than the pump alone provides. Remove two of the black plugs and replace them with filter disks over the open holes. That adds passive airflow around the clock, reduces excess moisture buildup, and supports healthier fruit development. Increase airflow gradually rather than all at once, and keep an eye on humidity as you do.
Step 4: Incubate your grain spawn
With the bath at temperature and the lid assembled, the chamber doubles as an incubator for your grain spawn bags. For most common varieties the ideal incubation temperature is 74–76°F. Follow your grain spawn guide through to fully colonized bags before moving on.
Water maintenance
Check the water level regularly. Some evaporation is normal — top it up as needed to keep the heater submerged, and replace the water every 10–14 days to stop algae or bacterial growth taking hold.
Two optional additions keep the bath cleaner for longer: a quarter cup of hydrogen peroxide helps prevent buildup, or one teaspoon of Myco Labs Eco-Cleanse keeps the water clean for up to 21 days.
Step 5: Spawn to bulk
Once your grain spawn bags are fully colonized, it is time to mix them with bulk substrate in the monotub.
First, install the thermometer/hygrometer in its permanent position: remove one of the side plugs, insert the round unit directly into the hole, and it snaps into place and starts reading temperature and humidity immediately.
- Wash your hands and wear clean gloves if you have them.
- Break the grain spawn apart inside the sealed bag first, so the colonized grains separate cleanly.
- Add the grain spawn to the monotub, then add your prepared bulk substrate.
- Mix thoroughly so spawn is distributed evenly through the substrate rather than sitting in clumps.
- Level the surface gently so it sits even across the tub, then put the lid back on.
The colonization period
Over the next 2–3 weeks the mycelium spreads through the substrate and the surface gradually turns white. During this phase:
- Keep the lid closed
- Hold 74–76°F
- Let the air pump continue on its incubation schedule
- No light needed
Once the surface is fully colonized, small pins begin to form — that is the start of fruiting.
Step 6: Install the LED light
Your system includes a low-heat 900 lumen LED grow light and a custom mounting adapter.
- Attach the mounting adapter by aligning it with the grooves on the black outlet base and pressing firmly until it clips in. Make sure it is fully seated and does not move.
- Mount the light using the pre-applied double-sided adhesive — on top of the lid, on a nearby wall, or above the monotub for indirect lighting.
- Position it slightly elevated from the lid. The light does not get hot and will not damage plastic.
Run it 12–16 hours a day and avoid strong direct sunlight. A second timer makes this hands-off. Worth remembering: mushrooms use light purely as a trigger to fruit and a direction to grow toward — it is not food, and more is not better.
Step 7: Fruiting conditions
| Parameter | Target |
|---|---|
| Temperature | 72–75°F |
| Fresh air exchange | Gentle and continuous from the pump, plus the added filter disks |
| Lighting | 12–16 hours per day |
| Humidity | Surface slightly moist, never soaked |
Do not spray directly onto the substrate. Small beads of moisture on the surface are exactly right. If it looks dry, lightly mist the inside walls of the monotub and let the humidity come up on its own. Spraying the substrate is the single most common way growers introduce bacterial problems into an otherwise healthy tub.
Step 8: Harvest
After pins appear, mushrooms size up fast and are usually ready within 4–7 days.
Harvest when: caps begin to flatten, the veil under the cap starts to stretch, and the mushrooms look full and firm.
How to harvest: grasp the base of the mushroom, twist slightly while pulling upward, and remove the whole mushroom cleanly from the substrate. Pick before spores drop — it keeps the substrate surface cleaner and improves the flushes that follow.
Flush cycles
After your first harvest, remove any leftover stems or debris, lightly mist the inside walls, and replace the lid at normal conditions. New pins typically form within 5–10 days, and most grows give 2–4 flushes. Each is usually a little smaller than the last, but quality holds up.
Cleaning after the final flush
- Remove and discard the used substrate
- Wash the monotub with warm water and mild soap
- Rinse thoroughly
- Let every component dry completely before reuse
Common mistakes to avoid
| Mistake | What it causes | Fix |
|---|---|---|
| Harvesting too late | Spore drop, messy surface, weaker next flush | Pick as caps flatten and the veil stretches |
| Misting the substrate directly | Standing water and bacterial problems | Mist the inside walls only |
| Letting the surface dry out | Pins abort, no new pinning | Watch for surface beading; mist walls when it disappears |
| Poor airflow during fruiting | Long stems, small caps, aborts | Move to continuous pump and add the filter disks |
| Large swings in temperature | Stalled colonization, uneven pinning | Let the water bath do its job; avoid moving the tub around |
If something on the substrate looks wrong rather than something about the mushrooms, our contamination identification and response playbook shows what each contaminant looks like and whether the grow can be saved.
Pro tipsConsistency beats intensity — steady airflow is better than bursts, and avoiding environmental swings matters more than hitting a perfect number. Check surface moisture daily. And take smaller, earlier harvests: they reliably lead to better second flushes than waiting for maximum size on the first.
Frequently asked questions
What temperature should I set the MycoClimate heater to?
It depends on your room. Below 60°F, set the heater to 78–80°F. Between 60 and 70°F, set it to 76–78°F. Between 70 and 74°F, set it to 75–76°F. Remember that this number is the water temperature, not the air inside the tub — your actual target is 74–76°F inside the chamber during colonization. If the internal thermometer reads above 76°F, lower the heater by one or two degrees.
How much water goes in the bottom tub?
About 2.5–2.75 gallons for the 44Q system and 3.1–3.25 gallons for the 66Q. Both give you roughly 4 inches of depth, which keeps the heater fully submerged while the two bases sit stable. Top it up as water evaporates, and change it completely every 10 to 14 days.
How often should the air pump run?
Run it on the included 24-hour timer, where each notch is 30 minutes. During incubation, 30 minutes every 8 hours. During early fruiting, 30 minutes every 2 hours. During heavy fruiting, leave it running continuously. Adjust from there: a well-ventilated room may need slightly less, and heavy condensation inside the tub means you should increase airflow.
Do I need to mist the substrate?
No — and you should not. Never spray directly onto the substrate. Small beads of moisture on the surface are the target. If the surface looks dry, lightly mist the inside walls of the monotub and let humidity rise on its own. Spraying the substrate directly is the most common way growers introduce bacterial problems into a healthy tub.
How long does a full MycoClimate grow take?
Bulk colonization runs 10–21 days after you mix spawn into substrate. Pinning begins once the surface is fully colonized, and mushrooms are ready to harvest 4–7 days after pins appear. Each following flush arrives 5–10 days after the previous harvest, with most grows producing 2–4 flushes. That is on top of the grain spawn incubation you complete before anything goes into the tub.
Why is there heavy condensation inside my monotub?
Too little fresh air exchange for the amount of moisture in the chamber. Increase the air pump cycle, and if you are at the pinning stage or beyond, remove two of the black side plugs and replace them with filter disks to add passive airflow. Raise airflow gradually rather than all at once so humidity does not crash.
Can I add MycoClimate automation to a monotub I already own?
Yes. The automation upgrade kits include the heater, air pump, tubing, diffuser, timer and lighting components without the tubs themselves, in 44Q and 66Q sizes to match your existing setup. If you already have monotubs you are happy with, the upgrade kit is the cheaper route to the same automated environment.
Does the LED light need to be on a timer?
It does not have to be, but it makes things easier. Mushrooms want 12–16 hours of light per day during fruiting, and a second timer handles that without you thinking about it. Light acts only as a fruiting trigger and a direction for the mushrooms to grow toward, so there is no benefit to leaving it on around the clock. Avoid strong direct sunlight.