Re: [compost_tea] Re: Pumping air in is not the best way to aerate your tea

From: <soilfoodweb_at_aol.com>
Date: Sat, 22 Feb 2003 10:10:08 EST

It's diffusion across the surface area of each bubble that is important for
moving oxygen into water.

Please do not confuse gas exchange with moving water around.

As the bubbles rise through water, gases are exchanged across the surface,
depending on the concentration of each gas in the water and in the air
bubble.
Diffusion of any gas is limited by the maximum concentration that can be held
in either the water, or the atmosphere, releative to temperature and air
pressure. The higher in temperature, the less gas can be held in water, and
the lower the atmospheric pressure (i.e., elevation), the less gas can be
held in water.

How can you tell if bubbling air through water is achieving your goal of
imparting oxygen into the water?

Measure oxygen in water deficient in oxygen. Then start bubbling. The
diffrence is rapid and very noticeable. Don't tell me it doesn't work.

When the organisms in tea are consuming oxygen at a rapid rate, you have to
replace oxygen. Does bubbling air through water work? Take some
measurements.

Does bubbling air through water move the water around? Put your hand in the
water before you start bubbling, and then after you start bubbling. Tell me,
is the water now moving?

Is bubbling air through water the most efficient way to exchange gas? Ah,
there are a couple other important factors that must be paid attention to
here. We aren't just bubbling for the joy of bubbling.

We can't kill THE ORGANISMS IN THE WATER.

I really dislike it when someone starts critisizing before they understand
the history, point and purpose of what is being done.

If you have a better idea about how to get oxygen into water, reveal what it
is. But to just say that air exchange using bubbling methods isn't the most
efficient is missing the point. There are more important factors going on
in making tea that prevents simply injecting air into water at high pressure.
 

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com
SFI Oregon, USA
SFI Australia
SFI New York
SFI Europe
SFI New Zealand




Received on Sat Feb 22 2003 - 11:12:25 EST

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