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Has Anyone Used An Air Curtain To Aerate Compost Tea?

David Trees


Joined: Mar 15, 2013
Posts: 8
I was at a hydorponics store in our town today and I spoke to a very helpful fellow who suggested using a length or two of aquarium air curtain, rather than air stones (as they clog).

I thought what a great idea. They come in 4 lengths,12", 24", 36" and 48". They are flexible and can be shaped to any shape. They are normally used in aquariums for exotic fish he said.

This is the kicker and a few questions... They have a kind of rubberised sheath around them to make them soft. They are also a little weighted to help them stay in the bottom of an aquarium.

So.. Has anyone used one for Aerated Compost Tea?

Does anything think that the rubber sheath might some how adversly affect the compost teas biologicals?

Any other thoughts and feedback if you've tried it would be great. Thanks
Jordan Lowery
volunteer

Joined: Sep 26, 2009
Posts: 1528
Location: zone 7
    
  11
Look into an airlift pump. You get a great efficiency for power used for the amount of water you use. It won't clog and it can easily be home made.


The ultimate goal of farming is not the growing of crops, but the cultivation and perfection of human beings. - Masanobu Fukuoka
David Trees


Joined: Mar 15, 2013
Posts: 8
Thanks for taking the time to write Jordan.

I didn't know what an air lift pump was...LOL

So, I reviewed some videos on YT. For me... They don't like they generate enough aeration IMHO. The videos made it look like it just created a stream of water that perculated out.
Mind you I know nothing about aquariums.

Of course I would guess that this might be purely down to the pump itself(??).

The recommended minimum aeration is 55l/min from sites that offer a suggest aeration volume.

Once again thanks for sharing your idea. I can try it at least as the pump I have is a really solid one with lines out.
Josef Theisen


Joined: Oct 12, 2012
Posts: 205
Location: SE Wisconsin, USA zone 5b
    
    7
David Trees wrote:Thanks for taking the time to write Jordan.

I didn't know what an air lift pump was...LOL

So, I reviewed some videos on YT. For me... They don't like they generate enough aeration IMHO. The videos made it look like it just created a stream of water that perculated out.
Mind you I know nothing about aquariums.

Of course I would guess that this might be purely down to the pump itself(??).

The recommended minimum aeration is 55l/min from sites that offer a suggest aeration volume.

Once again thanks for sharing your idea. I can try it at least as the pump I have is a really solid one with lines out.


I'm not sure if I am understanding you correctly here, but based on your last post, I thought you might be falling for a very common misconception in areation. Oxygen exchange and degassing of water happens at the surface. Using a bubbler does not "inject" oxygen into water like people tend to think. There is a very tiny amount of exchange taking place on the bubbles, but the surface area is too small and they move too fast to have any significant effect. What the bubbles do, is lift water to the surface where the vast majority of gaseous exchange occurs. The important thing is that the water on the bottom gets lifted to the to the top and circulated around.

As far as using a bubble curtain, I can't imagine it would hurt anything. Fish keepers are a picky bunch and many fish are much more fragile than the organisms in compost.

Hope this helps, I am also planning to try some compost tea this year.


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David Trees


Joined: Mar 15, 2013
Posts: 8
Hey Josef

OK so 3 things in reply...

1. Thanks so much for taking the time to reply...

2. Simply said... Yes, you are right. I thought that aeration (not oxygenation) happened in the length of the compost tea vessel because air is effectively being injected in and causing the microbes, bacteria, funghi to dislodge from the medium and multiply in the water. Things like unsulphated molases feeds them causing them to grow and multiply in the water.

3. So... Based on your comments/concepts; the best thing to do is move the air through the vessel in a way that excites the water(bubbles @ 55l/min) to the surface where the exchange takes place..

BUT/And... To make it super efficient, I need to find a way to also create some kind of surface to bottom circulation. Kind of like how cold air falls and then rise as it heats in a sense. (I have never heard/read, it explained as you have shared it.)

So the bubbles through an air curtain in the compost bag, which I was told/taught dislodges in a sense the good critters from the compost medium is ... Ummm, not true or redundanct according to your experience?

Therefore an airlift system is a better system as it takes water from low or a set height and pumps it up and effectively drops it back onto the surface of the water creating a splash or bubbles.

I know it might seem quite complex in some respects but the soils well being makes knowing worth it to me.

Or perhaps a combination of the two.. Airlift pump with air curtain. It isn't that expensive to create both. The pump has two lines and the air curtain is only £3.00 for a 3 foot lenght and an extra £1 for a 4 foot length and is weighted to keep it on the bottom...

Brilliant, great input... Thanks again for all the input so far. I am getting a better picture of how this works best now.
Josef Theisen


Joined: Oct 12, 2012
Posts: 205
Location: SE Wisconsin, USA zone 5b
    
    7
Using the bubbles to physically agitate and mix the compost, or as you say dislodge the microbes, is really a seperate function from areation. It stands to reasing, though, that mixing things well is a good idea.

I believe the air lift pump (which is simply an air stone in a pipe) is more efficient at lifting a column of water from the bottom to the top vs. just having an air stone without the pipe. Using both could be a good idea to mix and areate very effectively, but I think that just having an air stone is generally enough to keep things aerobic.
R Scott


Joined: Apr 13, 2012
Posts: 2503
Location: Kansas Zone 6a
    
  22
A curtain across the back of an aquarium starts a circular current across the whole aquarium. Up the back, across the surface, and down the front--mixing all the water along the way. A curtain should work very well in a square or rectangular tea container. For a round container, you really need an aeration ring that goes around the edge (up the sides, down the middle) or in the middle (up the middle, down the sides) to facilitate the mixing. Using a stone as an airlift pump with the discharge set to cause a swirl in the tank could help as well.

Anything is better than nothing, but you can spend a lot of money on aeration in a hurry if you aren't careful--way more than you get back.

In theory, the air curtains do not plug up as fast as stones and are cleanable when they do--but in practice I don't know how long that would be in tea.


http://www.treebytheseafarms.com/
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
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David Trees


Joined: Mar 15, 2013
Posts: 8
Hey R Scott,

Thank you for sharing your thoughts with me above. I appreciate your comments a lot. I have just bought a nice pump for a sensible price. Found those air curtains and a source for good quality low prices poly pipe.

I will be using it for the long term so the cost was worth it but I can see what you mean about spending too much cash, after visiting that Hydroponics shop. I am not tempted because of my experience and because I have clear sense of what I want to do in my PC self sufficient property once we get it on our return to Australia later this year.

I will think about the shape of the drum/vessel for the compost tea as I did not know about the way the currents run in square / rectangular fish tanks / vessels.

So a BIG thanks for that info.

Hope all is well with you and yours.

Cheers..
Josef Theisen


Joined: Oct 12, 2012
Posts: 205
Location: SE Wisconsin, USA zone 5b
    
    7
I have to agree with that. Thank you for your thoughts on the shape of the flow R Scott.

I was thinking about this thread just now and figured out what I am going to do for the 55 gallon barrel I am setting up this spring. I already have an aerator for a small pond that consists of a large air pump and two large stones. I am going to use some large diameter pipe as an air lift pump and position it in the center of the barrel somehow so the water is drawn up the center, can hit a mesh bag full of compost, and then circulate back down the sides of the barrel.
David Trees


Joined: Mar 15, 2013
Posts: 8
Now this looks like it could be the ticket from a aeration and a flow perspective. It is a YT video showing how to create flow using an airlift kind of system.

Looks good with the little pink ball circulating showing the flow and how they create it. They are Koi Carp pond enthusiasts who made this demonstration model.

http://youtu.be/I1uBybsdXHQ

They're either Dutch or Flemish writing (Belgium). I think it wouldn't be that hard to integrate this into a square water butt or a help with the flow.

What do you think?

Here is one more. The key seems to be go big with the pipes and the bubbles. It moves more water and therefore must aerate it better on the surface.

http://youtu.be/KSb81nHCpI8 - This is his 3rd modification.

This is a link to the pond forum where RicShaw discusses his design and on page 5 or 6 shows photos of it opened up and the bits with measurements of how he created it.

This guys set up was not very expensive at all. He did have an air pump that could pump about 30 litre / minute. I think it cost him sub $40.00US. The rest was some scrap water pipe some bends and end caps and that is it.
Mateo Chester


Joined: Jan 10, 2013
Posts: 148
Location: Zone 4b
    
    2
The airlift is a sound suggestion. I'd be glad to provide you with a great design for a 5 gallon bucket if you'd like. A strong enough pump, as indicated, is clutch. Aside from that, Tim Wilson has a website I've been trying to share with people around here that like to get into the nitty gritty of aerated compost tea making. He breaks it down very well in my opinion. Also has some of his own brewer designs you could get some ideas from. http://www.microbeorganics.com
David Trees


Joined: Mar 15, 2013
Posts: 8
Thanks Matt C.

I like the vortex concept. I hadn't seen it before, so your post was spot on and cool.

My only question is this; does it still spin as well with a big bag of compost/vermipost sitting in the middle of the vortext.

It's a good idea for perhaps mixing / aerating the Tea but, how does it "shake" the microbes out from the mesh bag...?

I was under the impression that this bag needs some good solid vibration from air stones like bubbles (not literally air stones) to shake the microbes out of the compost/vermipost medium.

That all being said... it gives me more food for thought and it is great that you shared the concept. I had been thinking about how I could make the mixture move from top to bottom and left to right too. So the images and videos confirmed something that I had been drawing and thinking about from a design/concept perspective.

I had seen Tim Wilsons site too, found it a bit hard to read though.

It's a pity it doesn't have pages for sections and better spacing for ease of reading, as the images and content are great. The images are brilliant.

Mateo Chester


Joined: Jan 10, 2013
Posts: 148
Location: Zone 4b
    
    2
I dont use a mesh bag. With he airlift system, and bubbling in general you get far better dispersion without it. Just dump your material in the bucket with the airlift and the cycle will begin. If particulate matter is of concern to you, you would then use that mesh bag to filter the material after it has been brewed.

On the spillage- none unless you fill your bucket too much. I go for 4 gallons h20 to a 5 gallon bucket. I always but the bucket on a big tray or rubbermaid bin lid because sometimes the bucket can foam and I find this to be the only real source of spillage based concern.
Mateo Chester


Joined: Jan 10, 2013
Posts: 148
Location: Zone 4b
    
    2
Also look into venturi system type brewers. The only this is you must make sure you use a pump that wil not decimate you microbes.. Youtube has a couple good vids
 
 
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