[compost_tea] Several Subjects (Sorry Jeff & Doc...) Mostly aeration...

From: Kirk Leonard <kirk_at_oregonatural.com>
Date: Sun, 16 May 2004 19:42:06 -0700
Sunday... good day.  Been taking in the discussion on several levels, and
have to speak up.  Hope I haven't offended with my agenda in the
past.  USNOP ACT acceptance is a critical thing for me, but I'd like to
think I have a pretty good handle on the technologies involved, too.  (And I
will be back at you with NOP news, no matter what...:)

The small tea machine questions and answers have been interesting, as has
the recent soaker hose exchange.  I can imagine there are different
tire/tyre
compound/chemical components in Australian vs US tires and hoses, so there's
another possible puzzle.  Personally, I'm with Elaine and Ted and think it
should be avoided.  It's easy to make or buy different aerators.

On available small tea machines, my take is KIS units are the best value
available today, but they're way too noisy and short-lived.  Quieter and
more energy-efficient linear pumps can provide air more reliably over a much
longer time than blowers. Bob's Bitti is a good machine, and if Alaska
Bounty has fixed their aerator they should be good  tea makers, too, but
small machines are easily home-made with good aquarium pumps and other
aerators.  I have no idea what's available outside of the US, and I don't
trust the recent Gardens Alive product, and SoilSoup kits are not good for
aerated teas, though they can produce good bacterial and nutrient teas, I
think.  Any reports on the Gardens Alive machine?  It was complete and cheap
but I still wonder about the closed and uncleanable container.  I recall
Terence was going to tell us about that.

Upshot is there aren't many small machines out there to select from, so I
imagine most folks are still making their own: fit up a good sized bucket
and a big pump and make a good aerator.  Most importantly, you want good
compost, but that's
another subject.

So what the heck is an aerator?  Most simply, it's a way of putting air into
water, and there are several ways to do that.  We've talked about
"micro-bubblers" and "discs" and "diffusion tubes" and "nozzles" and "pipes"
and "stones," and Ted has talked about a column that keeps free compost
stirred up and air inputted, apparently, and Frank has used free compost
methods.  I'd like to hear more about using free compost in a water
container.  Personally, I use a hand-stirred filter bag (800 micron -
20 mesh - monofilament nylon) in making tea so I don't have to filter it for
application.

Micro-bubblers are sewer plant tank aerators that are not suitable for
compost tea because they inject air in too small bubbles, apparently.  They
can keep DO up dramatically but are destructive of organisms in suspension.
I think they are disc-shaped.  Regular discs are usually perforated plastic
sheets mounted in frames that are weighted to stay on tank bottoms.  They
are
made for aquariums and provide appropriate-sized ACT bubbles.  Hard to keep
compost tea-clean, though, I hear.

Diffusion tubes are rubber or latex tubes with slots cut into them which
expand and release air when air pressure is applied.  Per Michael's
experience, I hear they don't stand up very long, and are hard to keep
clean.  Nozzles are what bobolators use -- simple plastic pipe endcaps (I
call them "wands":) with holes drilled in that release air at a single point
in a tank or bucket, or as in Bob's extraction chamber.  I look forward to
hearing how Bob is doing 500 gallons as I haven't seen it, but his new
air/water ratio of .75 sounds good.

Pipe aerators are half to three-quarter inch plastic pipes with air holes
drilled in them. Holes should be 1/16-1/4" -- little ones are good at
distributing air, big ones at moving water around and organism extraction,
but big holes need a lot of air capacity. Whatever size, they need
weighting, iron or stainless rods inside the pipe seem best, to stay
submerged (or under compost in a filter bag).

If you can conjure up a combination of pipes and joints and tees you can
make good home-built aerators with them.  If you can figure out how to bend
them for most ACT tanks and filters, that's even better, but it's hazardous
to the extent that most plastic pipes (US) are made of poly-vinyl-chloride -
pvc - and are toxic if burned or volatized.  Henry said he knew how to do
that safely and maybe he'll say more.  Don't use plastic cements in joining
pipes, et al, btw.  Unless you're using a pump with high pressures (> 10
psi) it's not needed, and you want to be able to take it apart for cleaning
every once in a while.  If your pump is so robust, use threaded fittings,
unglued.

Stones are porous, baked ceramic pipes or globes, usually.  Like discs and
pipes they can make good bubbles, but they are hard to  clean.  All of these
various aerators hook up via flexible, usually vinyl pipes, same as aquarium
piping, to an air pump.  I trust Mike's mention of not understanding why
anyone would use an air pump was a typo and he meant to say water pump...
Don't use a water pump unless all you want to do is stir the water.  If you
want to grow organisms in compost tea, use an air pump, the bigger the
better.

Which gets into another subject altogether and I've harped enough on it
several times, I think.  Need to hear from others.  Mike today posed the
question again: How much air to how much water?  Doc and Bob have
illustrated that depends on how much nutrients.  I agree, but I also am
convinced that higher air/water ratios are better, for accommodating higher
compost and nutrient loads, and for safer and higher fungal content teas.

Based on info gained here, a minimum air/water ratio (cfm air/cf water) is
.1.  KIS machines push 4.  Aussies seem to like 3.  Mike uses 2.  I think .5
is ok and Bob's now selling .75.  Are they smarter in Redmond or down under
or what?

Mike -- is a regenerative air blower the same as a rotary vane air pump?
I've asked this before and think that may be the case but I don't know.
Goshdarn these marketing names/ploys.  As I understand it, a rotary vane
pump is basically an impeller-style air pump that has slotted, movable vanes
that can accommodate back pressure, unlike regular blowers which are built
with fixed vanes to work at free air pressure -- basically no pressure --
and are easily beat up with any back pressure.  ACT pumps need to be able to
handle a little back pressure, as in the water they're pushing into...
Rotary vane pumps seem to be the best value for large volumes.  Am I stuck
in a Gast hole or what?

Gotta shutup.  Point is to get a good air pump and put it into the bucket
well.  The challenge of good compost is probably greater.  And let's show
USDA how stupid they are being on compost tea.  I actually think bad compost
might still be used to make good compost tea.

I appreciate feedback on any of these questions, thoughts and hypotheses.
Forward hoe!

-- Kirk















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Received on Sun May 16 2004 - 23:36:33 EDT

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