[Compostteas] D.O. levels - Testing Meters

Frank Teuton fteuton at sympatico.ca
Sun Jun 2 06:22:38 EDT 2002

> What is the foam that forms on the tea.  Someone told me you know when the
> tea is finished by a head of foam.  Is this true?

Not necessarily, I think, but foam is a 'sign' to look for. There is a tale
of foaming from saponin in the archives, see:


"Fungal foods -- saponin is good, but it foams to high heaven.  Bruce
shared his experience with me once -- everything was fine when he left late
evening, after putting saponin in the brew mid-afternoon.  When he walked in
early the next morning, his entire facility was waist deep in foam.  His
phone conversation with me was rather, ah....  but he came to appreciate
vegetable oil.  Just a few drops helps cut the foam.  But be careful of the
kind of oil - SOME canola oils and olive oils are anti-fungal.  You might
want to test before and after adding the oil to see what effect the oil had
on the organisms."---Elaine Ingham

> Has anyone tried making tea with the compost loose in the brewer and not
> adding any extra food source.  It seems like there would be plenty of
> soluble food and appropriate chunks for the continued growth of bacteria
> fungi.  Is this faulty logic?

Yes, the fault in it is that finished compost generally has few available
foods for the sort of bacterial growth that you get by adding supplemental
sugar-type foods. Composting is the microbial decomposition of raw organic
matter into a humus-like substance beneficial to plant growth, and the fact
that microbes have already had a full go at the stuff means that real
compost has little to offer in the way of food for bacterial growth, as far
as simple sugars and other readily available nutrients are concerned. The
composted nutrients are simply held in much less available forms.

A compost tea made from compost only plus water is not a bad thing, but it
will not have the numbers that a nutrient added compost tea will have,
microbially speaking.  As I understand Elaine's views of this, this means
that you would need a much greater volume of such tea to get the same sorts
of effects as a nutrient fed aerobic compost tea in the field.

However, a compost only tea might not need aeration, and so be more
copacetic with those not inclined to tap the grid for go juice. Will Brinton
has an article about these sorts of teas, see

> Can there be too much air in the brewer in terms of damaging organisms due
> to turbulence?

We have decided to keep it bubbly at least for starters in this regard. One
of the neat things about modern air diffusion technology is the choices that
exist between fine bubbles and coarse bubbles, the former being superior at
oxygen transfer and the latter excelling in the mixing department. Diffusers
are much less expensive than the pumping equipment, so playing around with
the bubble size mix should be reasonably cheap....
> Hi Frank,
> I also searched through the maze of the Aquatic Eco-systems catalog to put
> together a brewer.  I just ordered the components and have not received
> yet.
> My brewer is going to be about a 20 gallon system.  My tank is 12"
> 48" deep which I will fill about 36" with water (item no. T4)  I went with
> tall narrow tank because I was told that tall was better for oxygen
> diffusion.  I went for 3 of the Tetratec Deep Water pumps (DW96) as they
> almost gave me as much power as the small sweet water linear piston pump
> (SL22) but for less than half the price.  I'm using three .35 cfm
> 2 fine pore and 1 medium pore (Sweetwater).
> My plan was to put one of the diffusers in the tea bag (probably
> I was hoping just to put the tea into the tank loose but everything I've
> heard about post brew filtering is that you lose organisms.

As I noted to you in a private email, I see the advantages of loose compost
in a bubbling system as outweighing the disadvantage of having to strain.
The turbulence you noted above ought to be good at detaching fungi from
their matrix particles, so if as I visualize, the loose compost tea does a
better job of extraction, then straining it to go through the spraying
equipment ought not to hurt the tea any more than it would the other tea,

And, if you have a better tea and the point was to use it as a soil drench,
for example, you can use non-limiting application equipment, such as a
watering can or (ahem!) a mere bucket....

If you need to use a sprayer then straining to within the limits of that
piece of equipment is necessary in any case, isn't it? We are currently
fiddling with our straining and spraying equipment to find the most open
straining method consistent with not clogging the sprayer nozzles, and one
item that will be eliminated is the 80 mesh screen at the pump intake nozzle
in the sprayer, this thing clogs too much and probably excludes too many

Next batch we will see how the Tower of Microbial Power functions with some
larger material passing through the nozzles....
> What I don't understand is how filtering tea post brew can remove
> but putting the tea through a pump and spray nozzle doesn't.  That just
> doesn't jive in my head.

Your logic is impeccable. The quest is to put pretty darn chunky compost tea
into a fine enough spray to give good leaf coverage (that is our quest, with
apple scab being our principal adversary, at least) without losing the
needed organisms, as efficiently as possible.

For large scale commercial users a tea brewer that gives ready to go tea
that doesn't need a whole lot of further straining is nice because it
eliminates an additional step of filtration.

At some point we may see new equipment emerge; one type that interests me is
rotary atomization, such as the Proptec sprayer:


A company in the UK has some interesting products in the same vein:


The nozzleless nature of the rotary atomizers suggests the possibility of
moving chunky compost tea into a mist without having organism losing
straining going on, although I imagine there is some organism loss that is
inevitable in any kind of spraying.

Ultimately what we are about is not just making great tea in the vat, but
getting that tea out to the plants and soils, and getting it out in an
effective manner. There is a lot of work still to be done, as I see things,
to find the hot setups for the particular situations.

Hope that helps,

Frank Teuton

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