KIS Organics

50 gallon Microbulator (Compost Tea Brewer) - FREE SHIPPING

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  • Regular price $ 360.00
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Free shipping in Continental USA only. Does not include Alaska, American Samoa, Micronesia, Guam, Hawaii, Marshall Islands, Northern Mariana Islands, Palau, Puerto Rico, US Virgin Islands, Armed Forces Americas, Armed Forces Europe, or Armed Forces Pacific.

New & Improved 50-Gallon Microbulator!


This brewer does NOT come with a 55 gallon container.

* Active flow-circulation induced by air alone; 6.3 gallons/minute
* Efficient gas exchange system for excellent dissolved oxygen maintenance
* Works with or without an extractor bag (extractor unit included)
* Two different ways to configure apparatus
* Translucent barrel promotes the growth of phototrophic microorganisms
* 3.5 CFM diaphragm air pump with 1 year warranty
* Can be dismantled and cleaned in under 40 minutes, including the barrel
* Sturdy parts used in manufacture
* Specially designed machine slotted PVC diffusers
* Operational instructional videos included
* Inexpensive; $325 without barrel

From Tim Wilson of Microbe Organics:

The goal from the beginning was to provide an affordable, efficient device geared to the small farmer/grower who doesn’t need the fancy looking brewer, just one that works and is easily cleaned. During the end phase of development and testing I discovered that my device would not work in just any shape of tank so be sure you use a 55 gallon (US) barrel of the correct dimensions. 

My design, unlike other commercial brewers I have seen, does not just blow air into water or into the extractor bag but actively circulates the water while charging it with oxygen. This is done using only an air pump. No water pump is involved. This is accomplished by a diffuser housing fixture I designed and built which incorporates the diffuser inside an 1 ½ inch PVC pipe [1.25 inch industry size]. The whole 50 gallons of water is cycled through this pipe every 8 minutes at a measured flow rate of at least 6.3 gallons per minute. The water is drawn from two opposing sides of the bottom of the tank, pushed past the diffuser, while being injected with O2, up the pipe and through the return nozzle suspended about 2 to 5 inches above the water’s surface, falling back into the liquid, pushing O2 into the water by breaking the surface tension barrier, facilitating the release of CO2 from the tank and the absorption of O2 (gas exchange). This is not unlike the action of a waterfall or flow form. This action pushes the oxygenated water into the body of water further raising the dissolved oxygen content. Because the water intake openings are located at opposing sides at the bottom of the barrel, a current-like flow is created and maintained so any still areas of water are highly unlikely. The release of CO2 is essential to create space in water for the absorption of dissolved oxygen and the only way for CO2 to be released in a CT brewer is through the surface. At the same time a large slotted PVC diffuser is infusing the whole body of water with air. Oxygen is absorbed by the interface of the bubbles created on the way to the surface and the surface tension barrier is broken again by the bubble turbulence, allowing the further release of carbon dioxide and the maintenance of dissolved oxygen. By this means, there are three interfaces where O2 is being injected into the water or compost tea.

This highly efficient yet very simple method is generally able to raise and maintain the dissolved oxygen (DO2) content of fresh well water having a TDS/EC of 21 to 30 PPM and temperature of 18 C to 21 C (65 F – 70 F) at least 3 PPM (parts per million) above the natural DO2. Using the same water within the same temperature range, with; 4% compost/vermicompost, 0.75% black strap molasses, 0.25% kelp meal and 0.063% fish hydrolysate, the DO2 is maintained at 8.8 to 9.8 PPM up to a 48 hour brew time. Please note that these are maximum amounts of compost inputs and not recommended for people brewing without microscopes.

The circulating action, the force of impact with the water’s surface along with the air from diffusers provides sufficient agitation to break the microbes loose from their binding spots in the compost. The continuous flow provides a more homogeneous dispersal of oxygen and microbes, avoiding still water areas where potential undesired microbial life may develop. Once free swimming or bound to smaller particles, the bacteria, archaea, yeast cells and fungal hyphae graze on the feed supplied and multiply or grow.

Maintaining a reasonably high rate of dissolved oxygen in the body of water is essential to the device’s efficiency for extracting and multiplying the beneficial aerobic microbes, consisting of; archaea, bacteria, fungal hyphae, flagellates, amoebae, some ciliates, yeast cells and yeast fungal hyphae. Because of the constant cycling, microbes are fairly evenly distributed throughout the tank. To get a sample, simply hold a container under the return nozzle.

With Extractor Unit;
The Microbulator can be used in free suspension or with mesh extractor bag configurations. A specifically designed diffuser is used in the bag while the internal diffuser continues circulating the water/tea breaking the surface tension. Both configurations are good for multi-purpose compost tea but using the extractor radically reduces particulate matter in the tea and is good to use for foliar disease suppression. The extractor should be used if you are using coarse compost with pieces between 1/2 inch and 1 inch cubed.

The highest microbial numbers are going to be developed using the device configured for the compost placed in free suspension but if one requires the extractor for a reduction in particulate matter this configuration provides a comparative alternative.

Free Suspension;
On the farm we usually use the Microbulator 50 without the extractor, remove the apparatus once the brew is complete, allowing the particles to settle to the bottom, lower in a submersible pump just above the level of the spent compost/particles and pump out the clearer compost tea. Alternatively one can place the pump in a mesh bag (fly screen size) and drop it in or simply scoop out the compost tea with a pail or watering can. Afterwards dump out the thick leftover slurry onto your soil or compost pile. If you are using vermicompost any worm eggs/capsules/cases remaining will still hatch once in the soil or in a non-hot compost pile.

How about cleaning?

The whole unit can be dismantled and cleaned in under twenty minutes. Add ten minutes if you use the bag and another ten for the barrel. The unit should be removed from the compost tea while still pumping air for best results. This prevents back-flow into the diffusers and into the air tubing. While pumping air, particles and bacteria will have a more difficult time entering the air system. The whole unit then pulls apart and can be cleaned quickly with fresh water, a scrub brush or pad and a bottle/pipe cleaner (available at Wal Mart, etc.) If you clean the unit right after use, generally you can use water alone but occasionally you may wish to use hydrogen peroxide or bleach. It is not advised to use bleach on the extractor bag but you may use it on the pipe and tubing. You should not need to clean the inside of the air tubing if you prevent back-flow. The extractor bag should be flushed under fresh water immediately following use and can be hand washed using a peroxide product like Oxy-clean.

What about brew times?

Brew times are 24 hours using KIS Organics, custom made Pro Kit for the Microbulator.

I am confident that the Microbulator 50 will match or surpass any other commercial brewer as far as production of numbers and diversity of microbes and DO2 maintenance, given equal parameters of water, temperature, compost, foodstock and time. It is very important to be aware that you need good quality compost/vermicompost and feedstock to get good quality compost tea. Temperature and water quality must also be considered. Really, there can be so many variables and the best way to know at what hour your microbes are at the optimum level is by microscopic examination.

Customer Reviews

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Customer Reviews
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Marco D.
United States

Perfect. I even shaved it down to fit a 30g brute

Made it simple. Saves you the multiple trips to the store to get everything.

Tyler R.
United States United States

Splish Splash we're having a bath

The Microbulator overall seems like a good design. The thing splashes quite a bit of water when using. Which may or may not be an issue for you. I've put a trash can lid over the unit while in use to stop it splashing out of the barrel. The pump is nice and quiet. For the price I could have honestly built this for less. When I read the unit had some sort of a custom designed "diffuser" I thought it was something internal to the unit more than just some pieces of PVC fittings to build the base. Unless I'm missing a piece? Overall if it aerates as well as it claims I will be happy with the purchase.

United States

50 gallon Microbulator (Compost Tea Brewer)

Excellent, all-around, from customer service to the equipment.