If you're tired of running out of vertical space in your grow, the dub tub tek is probably exactly what you need for your next project. It's one of those methods that sounds way more technical than it actually is, but once you try it, you'll realize why so many people swear by it. Essentially, you're just taking two plastic tubs and flipping one over on top of the other. It's a simple solution to a common problem: mushrooms that want to grow taller than their container allows.
I remember the first time I used a standard shoebox setup. Everything was going great until the mushrooms hit the lid. They started curling, getting smushed, and the airflow just wasn't right. That's where the dub tub tek really shines. It gives your fungi the room they need to reach their full potential without you having to invest in a massive, complicated Martha tent setup or a huge monotub that's hard to hide.
Why the dub tub tek works so well
The logic behind this setup is pretty straightforward. By using two tubs—usually the 6-quart "shoebox" variety—you create a larger, controlled microclimate. The bottom tub holds your substrate and mycelium, while the top tub acts as a humidity dome. This extra headspace is crucial because it allows for a larger volume of air, which helps manage CO2 levels during the fruiting stage.
One of the biggest perks is the humidity control. When you have that second tub inverted on top, it creates a nice little environment where moisture can circulate. You'll see condensation building up on the walls of both the top and bottom tubs, which is exactly what you want. It keeps the surface of your substrate from drying out too fast, which is often the death knell for a good pinset.
Plus, let's be honest, it's cheap. You can grab these tubs at any big-box store for a couple of bucks. If you mess one up while trying to melt holes in it, you aren't out a ton of money. It's the perfect entry point for hobbyists who want to scale up just a little bit without going overboard.
Getting your materials together
You don't need a massive workshop to get a dub tub tek going. In fact, you probably have half the stuff in your kitchen or garage already. Here's the basic rundown of what you'll want to have on hand:
- Two identical plastic tubs: Usually the 6-quart ones work best for this specific style.
- Micropore tape: This is a lifesaver for managing airflow while keeping contaminants out.
- Substrate: Whatever you prefer, but a coir/vermiculite mix is the gold standard for many.
- Fully colonized grain spawn: Make sure it's healthy and white before you even think about putting it in the tub.
- Isopropyl alcohol (70%): You're going to be cleaning everything.
- A spray bottle: For misting your tubs later on.
When you're picking out your tubs, try to find the ones with clear lids and clear bodies. You want to be able to see what's happening inside without constantly lifting the top and messing with the humidity. Some people like to use black spray paint or a liner on the bottom of the lower tub to prevent side pins, but that's totally optional and depends on your personal preference.
The assembly process
Setting up the dub tub tek is mostly about timing and cleanliness. You'll start by mixing your colonized grain spawn with your pasteurized substrate in the bottom tub. Make sure you level it out nicely. You don't want it packed down like a brick, but it shouldn't be super loose either. A nice, even surface helps the mycelium colonize consistently.
Once you've got your bottom tub filled and leveled, you'll usually put the original lid on it and let it sit in the dark for a few days. This is the colonization phase. You're waiting for that white mycelium to take over the substrate. Once it's looking nice and fuzzy—usually about 70% to 100% colonized—it's time to bring in the second tub.
Take your second tub, give it a thorough wipe-down with alcohol, and flip it upside down over the first tub. Now, you've got a "dome." Some people like to tape the seam where the two tubs meet, leaving a few gaps for air, while others just let it sit there loosely. If you find your humidity is dropping too fast, tape it up a bit more. If things look too soggy, give it more of a gap.
Managing airflow and humidity
This is where the "art" of the dub tub tek comes into play. Mushrooms need oxygen to grow, but they also need high humidity. It's a balancing act. If you have the top tub sealed too tight, CO2 will build up at the bottom, and your mushrooms will grow "fuzzy feet" or come out looking like skinny little noodles because they're reaching for fresh air.
If you see those fuzzy white patches at the base of your mushrooms, it's a sign you need more fresh air exchange (FAE). You can fix this by fanning the tub a couple of times a day with the lid or by adjusting how the top tub sits. On the flip side, if the walls of the tub look bone dry, you need to mist.
When you mist, try not to spray the mushrooms directly. You want to aim for the walls of the top tub. The goal is to keep a fine mist of droplets on the plastic, which will evaporate and keep the air inside nice and humid. It's all about creating that perfect "spring morning" vibe inside the plastic containers.
Dealing with common hurdles
No grow is perfect, and even with the dub tub tek, you're going to run into some issues eventually. The most common one is contamination. If you see green, black, or weirdly bright yellow patches, it's usually game over for that tub. This is why being obsessive about your alcohol wipes and general cleanliness is so important during the initial setup.
Another thing to watch for is "stalling." Sometimes the mycelium just stops doing anything. This is often because the substrate is too dry or the temperature is swinging too wildly. Try to keep your grow area in a consistent temperature range—usually somewhere in the low to mid-70s (Fahrenheit) is the sweet spot for most common species.
If you find that your top tub is falling off or sliding around, a little bit of painter's tape can act as a "hinge." It makes it way easier to flip the top open, mist the walls, and then close it back up without having to realign everything every single time.
Why I prefer this over bigger setups
I've tried the massive 66-quart monotubs, and while they can produce huge yields, they're also a huge risk. If one of those gets contaminated, you lose your whole harvest. With the dub tub tek, you can have four or five small setups going at once. If one goes south, you still have the others. It's like the "don't put all your eggs in one basket" rule, but for fungi.
It's also much easier to move. If you need to tuck your grow away in a closet or move it to a different room because of guests, you can just pick up the tubs and go. It's low-profile, high-reward, and honestly, just a lot of fun to watch. There's something really satisfying about seeing your mushrooms finally reach that top tub and realize they have all the space in the world to grow.
Wrapping things up, if you're looking to upgrade from a basic jar or a small bag grow, this is the logical next step. It teaches you the fundamentals of environment management without requiring a degree in biology or a massive budget. Just keep things clean, watch your humidity, and let the dub tub tek do the heavy lifting for you. You'll be surprised at how much of a difference that extra bit of vertical space makes.