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Re: Green Smelly Water

That worked fine but last weekend when I went away for
a couple of days my DIY CO2 got sucked into the filter
by way of a siphon.When I got home on  Monday 
night the water was cloudy and the SAE's were gasping
for air at the surface.I quickly did a 50% water
change and added emergency oxygen tablets(oxygenex by
aquatronics).On tuesday I also did another 40% 
water change. From the CO2 accident I lost a total of
three SAE's. Here's the problem now though.

As soon as the yeast were exposed to a nutrient and
Oxygen rich environment, they switched into 'aerobic
mode' and started propagating.  As long as the raw
materials and Oxygen are available, the yeast will
multiply until O2 is depleted, nutrients are depleted,
or they reach an optimum population count that can
reach millions of cells per liter.  If you remove
water, introduce oxygen and the water contains the
necessary nutrients, the yeast just start reproducing
again.  Given enough nutrients and room for more
members of the species, yeast can deplete O2 in about
30 minutes.  It's what nature has designed them to do.

When the solution's temperature gets above 70 degrees
F, the yeast go off on all sorts of wild tangents,
producing ester and fusel compounds.  Esters are what
give ales their unique aroma and flavor.  Fusels are
what give you massive headaches from drinking poorly
made beer.

When they've run out of nutrients and there are no
sugars to ferment in anaerobic mode, yeast cells begin
to die off en masse, and the survivors begin
metabolizing the dead cells' contents in a process
homebrewers call 'autolysis.'  The smell can be
overpowering, ranging from wet rubber to rotten eggs
to sewer gas.

There are several species of bacteria that can compete
with yeast, and these are frequent invaders when the
brew is produced in less than sanitary conditions. 
The two most prevalant invaders are lactobacter and
acetobacter.  The first one lives in your mouth and on
your skin.  The second populates surfaces like kitchen
counters, spoons, glasses, etc.  If you didn't boil
your water and sugar together for at least 15 minutes,
cover it and cool the solution quickly, or if you did
not sanitize your fermenter with 5% bleach solution,
then you probably had some bacterial competitors in
there with your yeast and they went into the tank,

To make matters worse, neither the competing bacteria
nor the bread yeast flocculate well at all.  They stay
in suspension until flocculating agents are added.  
Gelatin, bentonite and baked, crushed eggshells are
frequently used to flocculate a stubborn yeast from
the brew.  When the infecting bacteria are detected,
the brew is discarded so I'm not aware of any means to
floc them out.  Cool temperatures can help as well,
but I doubt that you'd want to drop your water temp
into the low 50's...

There is hope.  Activated charcoal will remove most of
the yeast and the chemicals producing the pungent
odor.  However, given the extent of the problem you've
described, it may take many media changes to get the
upper hand.  Salt is highly toxic to yeast, and even
small amounts may let you get their population under
control well enough to allow your filtration system to
get them out.

In my DIY CO2 'system,' I have the fermenter below the
aquarium, and the system is sealed.  If a siphon is
formed, I want the aquarium water going into the
fermenter, not vice versa.  The sealed connection will
prevent the siphon from continuing until the tank is
drained, and the location of the fermenter will
prevent the solution from entering the tank.  I don't
use a venturi.  I just have a small bell that holds a
bubble of CO2, which is located near enough to the
pump intake to allow some circulation of CO2 enriched

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