This is a guest post from our resident compost tea brewer, my husband Terry.
If you've been following our Organic Garden Diary series, you know how much we LOVE our Compost Tea and how much it has improved the health of our soil and production of our plants. In the ten years since we have been actively working an organic veggie garden, we have never seen more lush and bountiful growth and more healthy and productive plants. In a prior post we talked about Compost Tea – what, why, how and the fact that since we used so much – 50 gallons a week – it can become costly to purchase as much as we need, so we built our own and promised a subsequent post on “How To” build your own Compost Tea Brewer! So here we are as promised…Compost Tea: How to Build a Compost Tea Brewer & Brew Tea.
As we talked about Actively Aerated Compost Tea (AACT) being the most beneficial, that is what we're going to build. All AACT brewers have the same fundamental elements:
I used the Rubbermaid Brute brand because I was familiar with it having owned one for some time. Tough, heavy duty and it's USDA Meat and Poultry Group listed, ensuring regulatory compliance for food storage and cleanability.
2. Bulkhead Fitting/and Spigot
I fashioned a spigot using a bulkhead fitting, PVC ball valve, two threaded connectors and 90 degree elbow and it's working great! Here is what I mean by “bulkhead fitting” very similar to what I used – Bulkhead Tank Fitting, 1/2″ NPT Female
3. Air Pump and tubing/framework :
EcoPlus 728457 80W Commercial Air Pump, 1300 GPH
The pump I used is a somewhat less powerful version of this same brand – it cranks out 1030 GPH and is adequate – but if I had to do it again I'd go for the more powerful version. The difference in cost is very modest and more air and more agitation to dislodge the microbes from the compost is beneficial. Make sure it comes with a multi-outlet divider – as in the pic – because we will be running multiple air lines from it.
I run three air lines from the pump. One to each side of the frame/base and one to an airstone placed directly beneath the compost “tea bag” to agitate and oxygenate the microbes contained in the compost. That requires a minimum of 15-18 feet of 1/4″ clear vinyl tubing.
We will also need to “split” the air supply from the tubing to ensure equal distribution so we'll need two “T” splitters to insert into the tubing like the one shown below.
5. Frame/Aeration Base:
I used 1/2″ PVC pipe to construct the octagonal base and the uprights from which we attach a cross-bar to hang the “Compost Tea” bag while brewing. Once complete, the structure will fit nicely into the Rubbermaid container. You'll need a minimum of 10 feet of 1/2″ PVC for the aeration base and the uprights plus a 16″ length of a smaller diameter for the “cross bar”.
Container and Spigot:
1 Rubbermaid Brute Heavy-Duty Container
1 PVC Bulkhead Fitting – female threaded
1 PVC Ball-Valve – threaded
1 PVC 90 degree elbow – threaded
Air Pump and tubing:
1 Commercial air pump – 1300 GPH or so – mine is 1030 GPH and is OK, but I wish I had a bit more power
20 feet of clear plastic tubing
2 “T” splitters
The image of the structure gives you a good idea of how all the pieces fit together to form the octagonal base and frame.
10 ft of 1/2″ PVC pipe
2 ft of 1/2″ CPVC pipe – smaller diameter
8 3/4″ 45 degree “slip” connectors – to join the octagon base pieces
2 3/4″ “T” connectors – “slip” on – plastic tubing/air supply from pump gets inserted to these
2 3/4″ “T” connectors – “snap” on – uprights to hold teabag crossbar hanger gets attached to these
2 3/4″ End Plugs – to cap tops of “T” connectors – airsupply goes into these
2 3/4″ 90 degree elbow – 1/2″ crossbar is inserted here from which to hang “tea bag”
1 Large Air Stone – attaches to airsupply, oxygenates and helps to displace the beneficial organisms from compost into our tea
1) Cut hole into side of Rubbermaid container to insert bulkhead fitting where you want to place the spigot- see the red mark on the container above – START SMALL!!! We need to ensure a “snug” fit.
2) Insert bulkhead fitting, assemble internal and external parts and tighten
3) Assemble spigot by threading connector into bulkhead fitting, attach ball valve to connector, thread the second connector in the valve and attach 90 degree elbow – Congrats! You've made yourself a container with a spigot, perfectly watertight and a with a robust flow!
1) Cut 6 5 3/4″ sections of the 1/2″ PVC pipe. Take 3 of the cut pieces and join them together with the 45 degree connectors – do this twice. These will be the two sides of our base that will eventually become an octagon once all pieces are joined together. The picture shows 8 sections, I then used 2 of them for the next step.
2) Cut 4 2 3/8″ sections of the 1/2″ PVC pipe.
3) Take the two PVC pipe End Plugs and drill a small hole in the center of each – the hole needs to be small enough such that the plastic tubing fits very snuggly – as watertight as possible. Again, start small and enlarge the opening as necessary to enable a very snug fit.
4) Cut two 6 foot lengths of clear plastic tubing and insert them into each of the recently drilled End Plugs. Pull approximately 6 inches of the tubing through the hole – remember it should be a very snug fit. Attach a “T” splitter to the short end of each of the lengths of tubing.
5) Insert the End Caps with tubing attached into the top of the slip on “T” connectors – as seen above. Make sure that tubing is not “kinked” and that the “splitters” will be in a position to distribute air to both sides of the assembly once the End Cap is placed firmly in the top opening of the “T” connectors.
6) Insert the four 2 3/8″ segments of PVC into each of the open ends of the “T” connectors
6) Join the two sides we made in Step 1 above with the “T” connectors by joining both sides with 45 degree connectors. We should have an octagon with “T” connectors on opposing sides and should look something like the image below.
7) Drill 1/16″ holes on the top of the PVC – evenly distributed about an inch apart into the PVC octagon base – about an inch apart. If you look closely at the image on the right you can see the ink dots I've placed on the PVC to mark the placement of the drill holes.
8) Place the “Snap On” T connectors on opposing sides of the octagonal base – as shown at right.
9) Cut two 3 foot lengths of PVC and insert one in each of the “Snap On” T connectors to form the uprights to hold the Tea Bag cross bar. Place the 90 degree elbow joints on the end of each upright, cut a 16″ length of CPVC pipe to insert into the elbows and at this point our structure is complete and should resemble the image below.
10) Take the completed Aeration Frame and simply insert it into the Rubber Maid container, connect the clear plastic tubing air lines to air pump, attach the third clear plastic line to the airstone and we have our very own 32 Gallon Compost Tea Brewer! Congratulations!!! You are ready to start brewing Compost Tea! Let's go make some Compost Tea!
Water – fill the container with water. We need to make sure we are using unchlorinated water – the chlorine will act to kill the very organisms that we are trying to grow! If you are using normal tap water, simply letting the water sit overnight – 24 hours or so – will allow the chlorine dissipate. Rain water, pond water or well water is fine as is.
Compost – the tea that you brew will only be as good as the compost that is used for the brewing. Ideally, you'll want well-aged, fully decomposed compost rich in the types of bacteria and fungi that we are seeking to reproduce in our tea solution. Compost is commercially available but we prefer to make our own compost from the fruit/veggie scraps, eggshells, coffee grounds/tea bags, etc from the kitchen and our yard and garden clippings, putting them into a bin just like this one and turning it occasionally. We try and keep our compost as “clean” as possible and avoid manure from any source to limit the risk of any harmful pathogens being introduced into the tea. For those of you new to composting, there are many resources available on the web and tons of books. I found this one on Amazon and it looks very informative.
Compost Tea Bag – you'll need a mesh bag to hold the compost during the brewing process. I hang the bag full of compost from the crossbar directly over a large air stone during the brewing process. Make the sure the mesh is not so fine as to limit the ability of the organisms to release into the solution. We'll need a bag large enough to contain at least 5 cups of compost. This Heavy Harvest Premium Compost Tea Bag, Large looks perfect for our brewer, but you might be able to find one at your local beer brewing store…that's where we did.
Nutrients – Our goal during the brewing process is to take the beneficial organisms contained in the compost, introduce them to our solution then provide them the resources to reproduce and multiply. For that to happen, we need to provide them with oxygen and food. Our air pump, aeration frame and air stone will provide them all the oxygen that they need. We have to provide a food source. There are thousands upon thousands of different “recipes” for compost tea, but here is what I use…..
Compost Tea Recipe:
Fill the container with water, place the compost in the “tea bag”, hang the bag from the cross bar of the frame. We want the bag to hand directly over the air stone. Turn on the air pump to begin the agitation/oxygenation process, mix the liquid together and pour the liquid into the water. Let the solution brew for a minimum of 24 hours. How do we know when it's done??? Smell…..when it begins to smell less “fishy” and more “dirty” – like the smell of fresh, rich soil, you're done! I typically let mine brew for 36-48 hours. One word of caution……DO NOT TURN OFF THE AIR SUPPLY! If the solution becomes oxygen deprived for any stretch of time, it will quickly become anaerobic – literally living without air – and harmful pathogens in our solution can result. If the tea smells rotten, putrid or foul in any way, throw it out. It has likely gone anaerobic and we do not want it on our plants or in our soil. Let your nose be your guide. Healthy tea will smell more similar to the earthy richness of fertile soil than it will to your garbage can! Once done, our tea is now ready to be put to work in the garden!
We use approximately 50 gallons a week on our 130 square foot garden – that works out to about 3/8 a gallon per square foot. Do your own calculations based upon the size of your garden. You can't “over tea” your garden. That said, if the soil is already saturated or in an overwatered condition, then it only stands to reason that we don't want to add any tea! The tea is beneficial to not only the soil, but also to the foliage. We apply the tea directly to the foliage with a watering can as well as the soil surrounding the plants. Keeping in mind that the tea contains nutrients and beneficial microorganisms for the soil as well as for the plants, watering your soil – an empty bed for example – will also be valuable. Good luck, welcome to the world of Compost Tea…..your garden will thank you!
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