top of page
RSS Feed

#131 - DIY 25-Gallon Compost Tea Brewer

We all know the benefits of using compost and worm castings in our gardens and plants, but many people are not aware of another way of using compost that is even more beneficial to your plants.

For those interested in a more natural or organic method of gardening, one of the most important things that you can do to help your plants thrive is to use compost teas and worm teas. In order to do that, you need a way to brew the compost tea or worm tea and that is what we are going to discuss today.

As some of you know, I have a Ph.D. in microbiology, so I understand the complexities of the biological ecosystem at the microbic level that is at work in the soil and interacting with our plants.

Many people think of plants as having roots that are basically one-way highways to deliver nutrients to the plant. The truth is it actually goes much deeper than that and as we are only just beginning to understand in the past few years the plants are actually communicating with the micro-organisms that live in the soil around the roots of the plant.

In exchange for the micro-organisms delivering nutrients to the plant roots to feed the plant with, approximately 40% of the sugars produced through photosynthesis in the plants are sent back down through the roots to feed the micro-organisms in a highly effective symbiotic relationship. The other 60% is used by the plant for growth, fruit production, etc.

The more beneficial micro-organisms living around the plant roots the better able the plant is to have access to the nutrients in the soil, so by using compost and worm casting teas we are adding billions of beneficial micro-organisms to the soil around the plants roots.

So, why would you want to use compost tea? The nutrients in compost tea are more readily available to plants than those found in dry compost. The beneficial organisms -- which include bacteria, yeasts and fungi -- that compost tea provides your plants helps suppress diseases by either creating a physical barrier against disease-causing pathogens or by competing with or attacking them. Adding compost tea to your soil also reduces the need to use synthetic fertilizers, and it helps improve plant growth and vigor. This improved health reduces the risk of plant death due to pests or diseases.

Compost tea when added to the root zone of plants has also been shown in university studies to cause vigorous root development in plants which enables the plants to be more drought tolerant.

Compost teas can either be applied to the plants as a foliar spray or applied to the root zone around the plant. Im my case, I use both methods. Once per month I apply a foliar spray to the leaves and stems of the plants and I follow a weekly root zone application schedule.

Over the years I have tried multiple types of tea brewers and brewing systems, many of which have been quite expensive. They all had their good points, as well as their drawbacks or limitations.

I finally found a home compost tea brewing system that incorporates the benefits of several of the other brewers that I have used over the years. However, this one doesn't have the drawbacks that they did. This is a tea brewer that you can build yourself right in your own home, and most of the parts to build it are available at Home Depot, Lowes, City Mill or just about any other hardware or home improvement store.

The best part of it is that you don't have to just take my word for it that it works. This particular compost tea brewer was designed by the Oregon State University Extension Service in Eugene, Oregon.

Even colleges and universities are recognizing the benefits of using compost teas for organic gardening and are devoting their resources to studying the benefits of using compost tea on crops to provide larger root systems, bigger harvests, less plant disease, and less damage from insects.

Not only did Oregon State University design one of the best compost tea brewers that I have ever seen, they made it available to everyone for free as Open Source so anyone can make one simply by clicking on the PDF link below to download the plans.

I have been borrowing the one pictured below for a couple months now to test it out and see how I liked the design and I decided that I liked it so much that I wanted to go ahead and build my own to see how difficult it is to build.

Once I had assembled all the necessary parts, following the PDF design supplied by Oregon State University that I posted above, I was able to cut all of the PVC pipe pieces and build the entire 25-gallon Compost Tea Brewer and have it functional in under 10 minutes by myself. It is extremely easy to build.

The compost tea brewer uses a 32-gallon Rubbermaid Brute commercial trashcan as the brewing tank. I also installed an optional ball valve at the bottom of mine to drain the compost tea from the brewer with.

PVC pipe is then used to create the air tube system inside the brewer tank. The system is designed to inject air from the ring in the bottom as well as from the vertical tube in the center into 25-gallons of water that is sitting inside the brewing tank.

The resulting aeration of the water is quite effective.

Either compost or worm castings are then placed inside an extremely fine mesh heavy duty bag like the Bioextractor Bag shown below made by Biological Systems, LLC which I ordered from DripWorks.

The Bioextractor Bag is attached to the horizontal pipe above the water with the builtin straps with buckle clip on the bag. This is absolutely the highest quality compost tea brewing bag I have ever had the privilege to use. It is a little expensive, but with normal use you can tell that it is made to last for years.

The vertical air pipe in the center of the brew tank hangs down inside of the compost bag which allows air bubbles to be produced both inside and outside of the compost bag for maximum aeration of the tea and extraction of the biological organisms.

This compost tea brewer does not use any old run of the mill aquarium air pump that you can pick up at Walmart though. Those will just not provide the amount of airflow that is required to make effective compost tea. You need a pump that provides a minimum of 1 liter of airflow per minute for every liter of water in the system. So for this 25 gallon brewer we have about 94 liters of water, so we need an air pump that can provide a minimum of 94 liters of air per minute. I recommend the Active Aqua brand commercial grade air pumps like in the photo below. I selected a 112 watt model that produces 110 liters of air per minute for $79.42 at Amazon.

Air pumps like these can be picked up at most good hydroponics supply shops or ordered online.

The system can be used for more than just brewing compost tea and worm casting tea though. As you can see from the photos above I am currently running the system without the addition of the compost bag inside it, just aerating the water. I am doing this to remove any chlorine and chloramine from the water before I use the water on my plants and to water my lawn with. This is one beneficial step that most people do not even think about when they are watering their lawns or gardens.

The chlorine or chloramine that cities and municipalities add to the water is meant to kill off any bad bacteria in the water to keep you from getting sick. Unfortunately chlorine and chloramine is stupid and cannot tell the difference between bad bacteria and good bacteria, it kills off all bacteria. If you use that water to water your lawn or garden, you are killing the beneficial micro-organisms that your plants and grass depend on for them to receive the nutrients in the soil.

Remember, soil is different than dirt. Dirt is dead, with no living micro-organisms in it. Soil on the other hand is alive and full of beneficial micro-organisms. Soil is a complete ecosystem full of insects, monopods, bacteria, fungi, and other micro-organisms and organic matter. If we use chlorinated water we are essentially killing off part of that microscopic ecosystem while we water our lawns and gardens. Over time we can do an extreme amount of harm to the soil and can end up turning it back into dirt by destroying that delicate ecosystem.

Before I use city water on my lawn or garden I will remove the chlorination from it by either allowing it to off-gas in an open bucket over a 24-hour period before using it, or aerating it for a couple hours as I am doing in the brewer above. I will simply allow the system to aerate the water for a couple hours until I can no longer smell any chlorine in the water. Then it is ready and safe to use on the lawn and gardens.

I also use this un-chlorinated water in my worm bins and to wet down my compost piles with. Remember that the compost pile and worm bins also contain a whole ecosystem of beneficial bacteria and micro-organisms breaking down organic material in them. If we use chlorinated water we would do damage to that delicate ecosystem as well.

So I am able to get multiple uses out of a easy to build DIY system that took me less than 10 minutes to complete from start to finish. The entire cost of all the parts necessary to build the tea brewer, including the air pump and the compost mesh bag ran me $201.29 and this system easily outperforms other commercially available professional quality compost tea brewers at over three times that price that do not even produce half as much tea in a batch.

Well, that's it for today.

Until Next Time,

Aloha & 73


bottom of page