I tried my hand at brewing some compost tea, but I think my pump was
too weak. The tea smells terrible. It's been "brewing" for about two
weeks now. I just added a new pump, but I'm wondering whether I
should just start from scratch or whether there's hope for this
batch? Might the beneficial microbes have already died by now?
On Nov 18, 7:43 pm, email@example.com wrote:
What you're smelling is the production of anaerobic organisms. They
create smells similar to vomit, urine, or alcohol. DO NOT USE IT ON
YOUR PLANTS. You could potentially do some major damage to your
plants. Good actively aerated compost tea should smell slightly
earthy or have no smell at all. The same goes for the compost you use
Here's a good starting place for information:
Also a great book is for beginners is "Teaming with Microbes" by Jeff
What were your inputs into your container? What size pump were you
using? There are many more variables to making good compost tea that
most people realize. Hope we can help!
Thanks for the replies.
The original pump I used came with a 5-gallon aquarium tank. I used a
5-gallon bucket to brew my tea so I thought I was in good shape.
Here's the process I used: I filled a 5-gallon bucket with water. I
took the aquarium pump and attached gang-valves to four separate
bubbling stones. I turned on the pump and let it run for a day to
eliminate any chlorine in the water. Then I put some nice, sweet-
smelling finished compost in a cheese cloth and set it on top of the
bubblers. So the beneficial bacteria could have a little chow, I added
a few teaspoons of molasses and stirred twice a day. It began to
foam, but man did it stink! So, where did I go wrong? My only guess
is that the pump was too wimpy to aerate the brew. Or perhaps that I
put the compost in cheese cloth instead of just dumping it in the
bucket? I hate wasting perfectly good compost, so any advice before I
try again would be appreciated.
Oh, and can I dump this awful concoction back on the compost pile?
On Nov 19, 3:37 pm, firstname.lastname@example.org wrote:
Okay, a couple of things:
1. I would not dump this material back onto your compost pile.
Basically, you've established that you've brewed up a bunch of
anaerobic organisms that you don't want on your plants. So why
inoculate your compost with them? Better to dispose of it and start
fresh. Did you know that plants can't tolerate alcohols beyond 1 part
per million? There just isn't room for these organisms in a healthy
soil food web, and you certainly don't want to introduce them
artificially through bad compost tea.
2. I have not seen any data supporting the use of cheese cloth. I do
know for a fact that 400 microns is the optimal mesh size to put the
compost into when using a mesh bag. This allows the fungi and
protozoa to escape, but keeps most of the particulate in the bag. You
can brew without any bag at all, as long as you have adequate aeration
so the compost doesn't just settle at the bottom of the bucket.
3. Aeration is key! You need to keep the dissolved oxygen levels
above 6% throughout the entire brewing cycle. This isn't easy to
measure without a meter, but to give you an idea, in our brewer we are
raising the water column over 2 inches. This means that when I turn
on the aeration, the water level is raised up over 2 inches higher
from the bubbles.
4. How much compost did you use? I use 1 heaping cup that is a
combination of 3 composts: vermicompost, alaska humus, and a fungal
compost. This increases the diversity of organisms and ensures that I
have a good starting group of microbes. All the composts have been
lab tested, so I know they contain the organisms I want. You may want
to consider adding another compost, but all you need is maybe 2 cups
total or 1 lbs. worth.
5. Molasses is a complex sugar source that tends to select for
bacteria. The fungi are what provide the disease suppression and many
of the other beneficial functions. Do you have any humic acid or
6. Air stones can be problematic. Make sure you clean them
thoroughly with hydrogen peroxide and wipe off any remaining biofilm.
Otherwise you'll sabotage your next batch before you even start
brewing. Data has shown that very little biofilm can significantly
reduce the levels of beneficial biology in your tea.
I know this is a lot of info. There's a lot that goes into making the
tea. Hope this helps though, and check out that link I posted!
Basically I'm in agreement with Tad but I'm wondering about the wisdom
of putting the compost in cheese cloth. I would remove the cheese cloth,
add a little more molasses, and pour the brew into another container and
continue aeration. Repeat pouring into another container for three to
four days. If the smell does not improve, return it to the compost pile
and start from scratch again without the cheese cloth. This is a good
time to practice as, at least in the northern hemisphere, where the
ground is cooling down and you can't expect too much growth from your
the ground is cooling down and you can't expect too much growth from your plants
Billy, that raises another question -- we're just now getting down to
the upper 30's at night. Will cold temperatures affect the brewing?
Wow, Tad, thanks for the in-depth response! You're obviously a well-
versed tea brewer. :)
Oh man, my current setup, which includes *two* aquarium pumps, barely
gets the surface of the water moving. So what you're saying is that
the water should be roiling like crazy, not just bubbling a bit?
Really, that little? One website I found said to fill a 5-gallon
bucket half full with compost! I probably used about five or six cups
in my first batch.
I'm afraid not. I always look for liquid kelp but all I can ever find
is fish emulsion around here. Would that be of any benefit?
Great advice to clean the air stones. I would have never thought of
Yeah Jeff, I'm nothing if not tenacious, not to mention a little
Thanks so much for the info here folks. I've got a few days off for
the Thanksgiving holiday and will try my hand at another batch of
Yeah, optimum temps for yeast are around 95 F. I'm guessing that the
same would be true for the other micro-organisms. Tad is right about the
alcohol but I have a hard time believing that you could be anaerobic
with an air pump, except at the center of your cheesecloth. You could
add the material back to your compost as the anaerobic organisms won't
survive the aeration. But you avoid all problems, if you just chuck it.
Try same approach again for a week. Pour bucket to bucket (as needed),
for additional aeration, if you detect off odors. Filter through a nylon
stocking, cheesecloth, or towels (cotton or paper), if you are planning
on spraying it as a foliar application.
What the hell you going to use it on at this time of the year? Using a
Just wanted to say *thanks* for all the careful input folks have
offered here. I truly appreciate it. Armed with this knowledge, I
hope to have a killer batch of compost tea!
Have a great holiday season. :)
On Nov 20, 7:46 pm, email@example.com wrote:
where the ground is cooling down and you can't expect too much growth from your
I have say, I am impressed with your tenacity! We'll get you making
quality compost tea I'm sure! I'm in agreement with Jeff about
starting over and brewing for somewhere between 24-36 hours. And less
is more when it comes to adding addition foods for the microbes in
your tea. Too much molasses and your tea can go anaerobic in a matter
of minutes, even if you're pushing a lot of air into your bucket.
Homemade recipes I've seen from Dr. Ingham called for some humic acid
and liquid kelp and maybe a little molasses. I can dig up the recipe
if you'd like.
As for optimum temps., you want to brew at the ambient temperature
you'll be applying the tea at. It makes sense really, you're
selecting for the organisms that are most successful at that
particular water temperature in your tea, so you want it to match the
temps that you're applying at. Optimum temps are 70-85 degrees F.,
though you can brew at up to 95 degrees (though you will need to cut
back on your foods). From 50-60 degrees F., you may need to increase
your brewing time and also add more foods, as the organisms will be
slower to reproduce.
As for filtering, I haven't seen any data relating to the use of
cheese cloth. Jeff, maybe you can help here. I know Jeff recommends
the use of large-size nylons (I can't remember the specific size that
fits over the bucket). I assume that would be larger than 400 microns
when stretched, so any fungi and protozoa should be able to make it
through the filter. You don't want the filter to be catching your
larger beneficials though, so make sure you're not straining it too
I know in Florida this time of year, many people are using the tea.
Here in Seattle, we're done spraying for the year. We typically try
to get one last application down on the leaves that have fallen and
been mulched to speed up their decomposition over the winter and
increase the organic matter in our soil come spring time.
By the way, I don't mean for my posts to be discouraging in any way.
I think it's great that you're giving it a shot in making the tea. I
really am talking about optimal conditions with everything I'm
listing. You may not be maximizing the extraction and replication of
these organisms in your brewer, but that doesn't mean it won't be
beneficial. I say go for it and experiement. Try a few different
recipes on the similar plants or patches of your yard and see how it
responds. If you want to get really scientific, you can send in a
sample to Soil Food Web or look at your tea under a microscope. Where
are you located? If you're close to Seattle, you can send me a sample
and I can take a peek at it for you.
where the ground is cooling down and you can't expect too much growth from your
Here's that recipe I was talking about from Dr. Ingham:
5 gallon brewer
1 lb. of compost (I tend to prefer volume, as weights will vary with
1/2 cup of humic acid
1 to 3 T. of kelp
1 teaspoon of non-sulfured, blackstrap molasses
Check biology when you are done. If fungi are too low, up the humic
acid or lower the molasses
Bacteria and fungi compete for food. High bacteria mean low fungi,
unless you get the right balance of foods for them to both do well.
Wow, two weeks brewing???? You ran out of food for the organisms a
long time ago. Dump it out. Clean up and start over again. Try it
first with just a teaspoon of molassas and 24 hours.....
Teaming with Microbes: A Gardener's Guide to The Soil Food Web....
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