Re: [compost_tea] Re: Air Required + Measuring

From: Robert Norsen <bnbrew_at_yahoo.com>
Date: Wed, 8 Oct 2003 21:49:58 -0700 (PDT)

Below: Bobs words in bold.

Kirk Leonard <kirk_at_oregonatural.com> wrote:
In compost_tea_at_yahoogroups.com, Robert Norsen <bnbrew_at_y...> wrote:
> We just finished 9 ACTt runs in the SFI lab 3 identical
machines, identical quntities of compost, identical nutrients in identical time periods, identical water& water temps. We observed continuous DO2 readings during the test runs, each O_at_ meter located in identical locations relative to water activity to keep the probe accurate. Near the low points of the O2 use curve of the three composts being tested read 3.2, 7.8, 5.7 this variation was typical but fluctuated from all three at 7.8 near the start to the variation noted above.
> Our conclusion up to this point is that O2 demand is extremely variable depending on compost and/or nutrients. There are so many variables including the compost itself there may be only one way to
select O2 input SYTEM :
> . PUT IN MUCH MORE AIR THAN IS NORMALLY NEEDED MOST OF THE TIME <
Are you yelling now, Bob? How do we know "how much air is normally needed" Not yelling yet Kirk, but have an urge. Kirk goes on: if we haven't tested for differences in air volume, which you apparently
didn't do in the tests you mention? I appreciate the quest for a
predictable recipe, but I'm talking about differences in tea quality resulting from air volumes, all else held constant. I agree variations in
compost and nutrients are likely to change air requirements but how do we
know where to start? We're just guessing until we've done some testing at different air volumes.

Among other stuff we were aiming to establish is how much AIR. So the first thing we proved as we held AIR a constant, was that the amount of AIR is very different for equal temp, gallons, nutrient and quantities of three different composts. Your turn now Kirk, design, operate and pay for a test that will establish the AIR required under all conditions.


Dennis asks a real good question, too. Are you sampling DO in the tank or
using grab samples? In-tank sampling could account for the variability in You are saying that grabing samples from the brew in a separate container is better than a continuing sample submerged IN the brew? No way!
and of itself, seems to me. I'm not saying in-tank testing isn't useful,
just that getting a bead on DO differences among machines probably requires
grab sampling and measurement out-of-tank. Also, if the three measures you
state are from three different runs (times), it's quite possible the Lets see - how different can 3 identical systems 8" apart at identical times, temps and water conditons are going to be affected by different atmospheric conditions???
differences are due to barometric/atmospheric pressure differences during
the runs. And as I recall from Kevin's description, you were testing with (Ground Up ( Wood based) AH alaska Humus, Paul Sachs North country Organics from Vermont )
different composts, right? That info would be interesting to hear along
with DO diffs.

I disagree that the measuring method I suggested is "an all-day affair," and
in my experience yours is definitely not "really exact" -- in the process of
getting the bag onto the tank, there is no way to keep air out. Freeboard Hey Kirk read my method again there was no bag in a tank. You question our methods like i didn't have years of engineering including test projects. air is irrelevant but air in the bag is not. Further, how are you gonna use
a plastic kitchen bag on a big KIS, or better yet, a WormGold unit, or your
own 250 gallon unit? No can do with any bag I've ever seen. If you use a
hefty enough piece of plastic for the tank cover you can re-use it (on any
number of machines if you cut the sheet big enough, too), in which case the I find your method ridiculous
method I suggest would be quite quick and easy, as only measuring bag needs
prep. And how do you account for pump phase differences?

I can't find your original method description. Would you re-post, perhaps
with a little more detail? Maybe I did something wrong.
-- Kirk

Just re-read and don't complicat the methods I used Kirk. They are simple, accurate, practical and based on good engineering, physics and bio . Bob



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Received on Thu Oct 09 2003 - 21:34:55 EDT

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