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Re: [compost_tea] Re: Pumping air in is not the best way to aerate your tea
This issue has of course been discussed in the past in great detail. Dr
Ingham has pointed out that both air and water pumps can be used, often
together. If a water pump is used alone it is best to add air via a venturi
setup, as is detailed in the article below, linked to the one you yourself
give here:
http://thatwebplace.hypermart.net/aquatic/seascope/aeration.html
The issue with water pumps and their associated plumbing is one of organism
survival. Impeller mechanisms and 90 degree turns in the plumbing can cause
organism kill, reports Dr Ingham.
Pumping air is rather gentler on the organisms, and particularly is easier
to do when the compost is placed loose in the brewer, rather than contained
in some way.
For example, loose solids in the brewer can clog water pumps and mechanisms
like those of the SoilSoup machine.
Airstones too can get clogged over time, but usually not in the time frame
it takes to make tea. They are not difficult to clean and not expensive to
replace.
The size of the bubbles matters in aeration, as does the depth of the
vessel. Small bubbles in a relatively deeper system will give greater gas
exchange than large bubbles in a shallow system.
It is no accident that large brewers are almost entirely made from cone
bottom design structures. These structures offer optimum depth for bubble
aeration, optimum surface area for gas exchange, prevent pockets of
anaerobia from forming in 'dead zones', work well with loose compost, and
are easy to clean when the tea is done.
Water pump systems that work well in compost tea brewers do exist, of
course. See the brewers at www.composttea.com for example; the 22 gallon is
a water pump venturi setup, the 100 and 500 gallon use both water/venturi
and an air pump with air stones. Note that all the systems I know of with
water pumps also use venturi air additions...somehow those little bubbles
really are doing something, eh?
There are also systems which use only air pumps and air diffusers (stones,
tubing, discs, etc) and make good tea.
http://www.simplici-tea.com
http://www.alaskagiant.com/alaska_bounty_brewers.htm
Interestingly, flowforms have been used for tea making, and they, of course,
provide very much surface area for gas exchange (uptake of oxygen and
release of CO2). Problems of anaerobic pockets have occurred in the holding
tanks, though....additional aeration/agitation was needed there.
Much of this can be learned by going through Dr Ingham's e-zines, available
in .pdf format at www.soilfoodweb.com
I have debated someone else with the 'aquarists' dogma' before, at
www.wormdigest.org on the forum. Most of that was around whether a long
shallow tank was better than a tall deep tank, where aeration was available.
See:
http://www.wormdigest.org/forum/index.cgi?read=19907
and the other comments in that thread, and:
http://www.wormdigest.org/forum/index.cgi?read=19998
and comments in that thread, as well.
Bottom line: pumping air is a fine way to aerate your tea. Data show that it
works. It isn't the only way, but it certainly is a convenient way, less
costly on a small scale and certainly less annoying if the compost is loose,
than a clogged non-functional powerhead or similar pump.
Been there, done that.
Frank Teuton---has considered the whole pumping air argument from a number
of perspectives...
----- Original Message -----
From: <elprune@yahoo.com>
To: <compost_tea@yahoogroups.com>
Sent: Saturday, February 22, 2003 3:34 AM
Subject: [compost_tea] Re: Pumping air in is not the best way to aerate your
tea
> Sure can.
>
> I would check with the following sources:
>
> Any state water quality program (Wildlife)
>
> Aquarium industry (Fish life)
>
> Hydroponics industry (Plant life)
>
> Here are a couple of links that will get you started:
>
> http://saltaquarium.about.com/library/weekly/aa122997air.htm
>
> http://www.hagen.com/uk/aquatic/basic/3-6.cfm
>
> It's not the oxygen in the bubbles that's important, it's the water
> movement that they create. There are better ways to get water
> movement than blowing bubbles.
>
> If you find that using bubbles is the best way, please let us know
> why!
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