Compost tea activator – this page is being edited and updated

I was looking online for ways to improve the effectiveness of aerobic composting when I found a lot of information about using air to activate compost is solution. In other words, pumping air through compost tea. There are so many videos on YouTube that I can’t credit them all. Suffice to say, it’s not an original invention of mine.

The theory is that all the extra oxygen gives the bacteria and chemical reactions a kick and makes them more effective. I decided to give it a go. Here is the build that I chose to do.

Components & building the aerator

As usual, I was pretty flexible on the design, using what I had sitting around in the shed. You may see different options at your place.

First, we need a big container. Large enough to make a reasonable amount of brew. I chose a standard, 60L plastic garbage bin, available from all hardware stores.

Then, we need an air pump. I used my trusty (if rather old) 70L/min compressor. Thick aquarium hose and a couple of adaptors that I had laying around provided the means to get the air from the compressor to the bin.

fittings and tape
Scrounged fittings and lots of white plumber’s tape.

The biggest choice was the choice of pipe size and layout, then the number and size of the holes that would allow the air out while mixing it with the liquid in a way that would allow for maximum aeration.

I chose 15mm PVC pipe (because it is the smallest rigid pipe I had) and the ‘crosshair’ design that you can see in the pics.

Layout of the aeration bed
Layout of the aeration bed
Fitting snugly into the bottom of the bin.
Fitting snugly into the bottom of the bin.

The fiddly bit was to get it all to fit flush with the bottom of the bin. That took a couple af disassemblies and recuts but was eventually done. I decided that the inlet should be through the side of the bin, then continued that pipe across to the middle of the bin to suspend the compost bag from. It just looked better that way.

A t-piece allowed a second run of pipe to allow the air down into the aeration bed (flashy name – I came up with it myself!) and to act as a support for the cross piece and bag.

Aeration bed assembled.
Aeration bed assembled.

2mm holes were selected (because that’s the smallest dril bit l had that didn’t break). I placed 2 holes in each of the shorter sections, 3 in the longer. At this stage, I didn’t drill into the connecting pieces (tees and elbows) because they cost money!

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It all came together over an hour or so. Not because it was difficult, but it took a while because I was fiddling with the design as I went along.

Test #1 was a good blow through the pipe via my mouth. That worked OK. The next went flawlessly to, so the compressor was attached and let loose. No problems there either.

Options

With all of these DIY projects, there is more than one way to do them.

You don’t need to use PVC pipe, 13 mm poly pipe will do the job equally well. You can get the cross connectors locally in 13 mm but not in 19 mm or over.

For this one, you can do away with the central cross piece if you want and just run a loop of softer pipe about half way out from the centre. It’ll need a bit more pressure to give a good mix but will do the job