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

From: Mike Harvey <mharvey_at_westnet.com.au>
Date: Mon, 17 May 2004 14:54:28 +0800
You said.
..............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............
Not all disc shaped diffusers are micro bubble size - they can range from
large to medium to micro.
The problems with bubble size as I understood it related to varying bubble
size leading to different rates of ascent in the bubble, this then resulted
in shearing of the fungal hyphae. So as I understand it a consistent bubble
size is important. Ultra small bubbles are not good so we are told (based on
research). However it must be realised that bubble size is critical to
transfer of the oxgen into the water, smaller bubble size means huge
increases in Oxygen transfer rate. This is one of the reasons why how much
air for  compost tea ends up with the reply- it depends.
regards Mike Harvey
New Life Soils





----- Original Message -----
From: "Kirk Leonard" <kirk_at_oregonatural.com>
To: "Compost Tea Group" <compost_tea_at_yahoogroups.com>
Sent: Monday, May 17, 2004 10:42 AM
Subject: [compost_tea] Several Subjects (Sorry Jeff & Doc...) Mostly
aeration...


> 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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> Yahoo! Groups Links
>
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Received on Mon May 17 2004 - 11:33:04 EDT

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