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Old 26-02-2004, 10:08 PM
Ken Pinard
 
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Default DIY CO2 system question

I have been running my first DIY Yeast CO2 system. I of course did
everything not quite the way discribed:

I used a one gallon plastic milk jug. Filled it half full and put in extra
sugar (about 3 cups). added 1/8 teaspoon baking soda and 1/8 Teaspoon yeast
(standard red what ever it was). I put a diffuser in the tank (Bell type -
plastic pop bottle with the sides cut out.)

It has been running for three weeks and is still going strong. the bell
never empties and it occasionally releases excess CO2.

So now the question: I know that the yesat solution will get Alcohol in it
before it dies. Since I used a large container, can the alcohol get into the
tank to posion (inhibriate) my fishies? How much of a problem should I watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along better.

Thank you,

Ken



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Old 03-03-2004, 10:16 AM
bannor
 
Posts: n/a
Default DIY CO2 system question

On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:
snip
So now the question: I know that the yesat solution will get Alcohol in it
before it dies. Since I used a large container, can the alcohol get into the
tank to posion (inhibriate) my fishies? How much of a problem should I watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along better.


Ken, I am sorry... I must have missed this post when you first put
this question out there.

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.
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Old 03-03-2004, 10:32 AM
bannor
 
Posts: n/a
Default DIY CO2 system question

On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:
snip
So now the question: I know that the yesat solution will get Alcohol in it
before it dies. Since I used a large container, can the alcohol get into the
tank to posion (inhibriate) my fishies? How much of a problem should I watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along better.


Ken, I am sorry... I must have missed this post when you first put
this question out there.

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.
  #4   Report Post  
Old 03-03-2004, 10:38 AM
Ken Pinard
 
Posts: n/a
Default DIY CO2 system question

Thank you,
I have the bottle below the tank as well. I did put a little Baking soda
in but not as much as you suggested. I am using a 2 liter bottle now. The 1
gallon milk jug didn't hold the pressure well. That was my first attempt it
was interesting to see how it worked. I have adjusted my duffuser now to all
better circulation through it and to keep it lower beneath the plants.

Ken

"bannor" bannor -at- echoes - net - mind the spam block wrote in message
...
On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:
snip
So now the question: I know that the yesat solution will get Alcohol in

it
before it dies. Since I used a large container, can the alcohol get into

the
tank to posion (inhibriate) my fishies? How much of a problem should I

watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around

the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do

weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along

better.

Ken, I am sorry... I must have missed this post when you first put
this question out there.

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.



  #5   Report Post  
Old 03-03-2004, 10:42 AM
bannor
 
Posts: n/a
Default DIY CO2 system question

On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:
snip
So now the question: I know that the yesat solution will get Alcohol in it
before it dies. Since I used a large container, can the alcohol get into the
tank to posion (inhibriate) my fishies? How much of a problem should I watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along better.


Ken, I am sorry... I must have missed this post when you first put
this question out there.

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.


  #6   Report Post  
Old 03-03-2004, 10:43 AM
Ken Pinard
 
Posts: n/a
Default DIY CO2 system question

Thank you,
I have the bottle below the tank as well. I did put a little Baking soda
in but not as much as you suggested. I am using a 2 liter bottle now. The 1
gallon milk jug didn't hold the pressure well. That was my first attempt it
was interesting to see how it worked. I have adjusted my duffuser now to all
better circulation through it and to keep it lower beneath the plants.

Ken

"bannor" bannor -at- echoes - net - mind the spam block wrote in message
...
On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:
snip
So now the question: I know that the yesat solution will get Alcohol in

it
before it dies. Since I used a large container, can the alcohol get into

the
tank to posion (inhibriate) my fishies? How much of a problem should I

watch
for?

I have 25 gal tank with 14 small (1 inch mostly) fish. 4 plants around

the
difusser. pH is 6.6, Kh around 5. 0 nitrates, nitrites, ammonia. I do

weekly
water changes of 20%.

The fish are a bit agitated this morning. Normally, they get along

better.

Ken, I am sorry... I must have missed this post when you first put
this question out there.

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.



  #7   Report Post  
Old 03-03-2004, 06:03 PM
bannor
 
Posts: n/a
Default DIY CO2 system question

On Wed, 03 Mar 2004 10:07:45 GMT, "Ken Pinard"
wrote:
Thank you,
I have the bottle below the tank as well. I did put a little Baking soda
in but not as much as you suggested. I am using a 2 liter bottle now. The 1
gallon milk jug didn't hold the pressure well. That was my first attempt it
was interesting to see how it worked. I have adjusted my duffuser now to all
better circulation through it and to keep it lower beneath the plants.
Ken


Yeah, I am not surprised about the milk jug not holding the pressure.
I use 2 X 2 liter bottles on each plant tank... and rotate their
changes of media so that I am never without CO2 production.

The only time I ever had a leak from the 2 liter bottles was when it
was knocked over on it's side... the pressure from the CO2 forced the
fluid up into tank... fortunately I caught it before I lost too much
fluid... of course, it was a mess to clean up... i had to force bleach
through the tubing, bubble counter etc then flush it very well with
clear water and start the whole system back up again. I lost about
1/4 cup total fluid up into my tubing etc, so less than that actually
made it into the tank.. fish etc survived well, but I made a 30% water
change that day and the following day just to be safe.

I have seen someone advertising acrylic racks for holding 2 2 liter
bottles on aquabid... that will probably be my next purchase, 3 or 4
of those should suffice for my current setups...
  #8   Report Post  
Old 03-03-2004, 06:25 PM
bannor
 
Posts: n/a
Default DIY CO2 system question

On Wed, 03 Mar 2004 10:07:45 GMT, "Ken Pinard"
wrote:
Thank you,
I have the bottle below the tank as well. I did put a little Baking soda
in but not as much as you suggested. I am using a 2 liter bottle now. The 1
gallon milk jug didn't hold the pressure well. That was my first attempt it
was interesting to see how it worked. I have adjusted my duffuser now to all
better circulation through it and to keep it lower beneath the plants.
Ken


Yeah, I am not surprised about the milk jug not holding the pressure.
I use 2 X 2 liter bottles on each plant tank... and rotate their
changes of media so that I am never without CO2 production.

The only time I ever had a leak from the 2 liter bottles was when it
was knocked over on it's side... the pressure from the CO2 forced the
fluid up into tank... fortunately I caught it before I lost too much
fluid... of course, it was a mess to clean up... i had to force bleach
through the tubing, bubble counter etc then flush it very well with
clear water and start the whole system back up again. I lost about
1/4 cup total fluid up into my tubing etc, so less than that actually
made it into the tank.. fish etc survived well, but I made a 30% water
change that day and the following day just to be safe.

I have seen someone advertising acrylic racks for holding 2 2 liter
bottles on aquabid... that will probably be my next purchase, 3 or 4
of those should suffice for my current setups...
  #9   Report Post  
Old 04-03-2004, 06:17 AM
N. Wise
 
Posts: n/a
Default DIY CO2 system question

From: bannor bannor-at- echoes - net - mind the spam block

On Wed, 03 Mar 2004 10:07:45 GMT, "Ken Pinard"
wrote:
Thank you,
I have the bottle below the tank as well. I did put a little Baking soda
in but not as much as you suggested. I am using a 2 liter bottle now. The 1
gallon milk jug didn't hold the pressure well. That was my first attempt it
was interesting to see how it worked. I have adjusted my duffuser now to all
better circulation through it and to keep it lower beneath the plants.
Ken


Yeah, I am not surprised about the milk jug not holding the pressure.
I use 2 X 2 liter bottles on each plant tank... and rotate their
changes of media so that I am never without CO2 production.

The only time I ever had a leak from the 2 liter bottles was when it
was knocked over on it's side... the pressure from the CO2 forced the
fluid up into tank... fortunately I caught it before I lost too much
fluid... of course, it was a mess to clean up... i had to force bleach
through the tubing, bubble counter etc then flush it very well with
clear water and start the whole system back up again. I lost about
1/4 cup total fluid up into my tubing etc, so less than that actually
made it into the tank.. fish etc survived well, but I made a 30% water
change that day and the following day just to be safe.

I have seen someone advertising acrylic racks for holding 2 2 liter
bottles on aquabid... that will probably be my next purchase, 3 or 4
of those should suffice for my current setups...


I have experienced the same problem with 2 liter pop bottles falling over. The
problem is the bottom is not a very stable surface. To solve this, I switched
to 1/2 gal plastic juice bottles. They have a flat bottom that doesn't tip
easily and they are made of a much more sturdy plastic. And fruit juice is
better for you than pop, didn't your mom ever teach you this?


Nick Wise
http://members.aol.com/nwwise01
  #10   Report Post  
Old 05-03-2004, 04:30 AM
Morten
 
Posts: n/a
Default DIY CO2 system question

Bannor,

"bannor" bannor -at- echoes - net - mind the spam block wrote in message
...
On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.


The addition of baking soda (2NaHCO3) will not lower the amount of alcohol
(CH3CH2OH) on the solution unless you put so much if in there that it lovers
the pH too much below 5 effectually killing the yeast before it gets a
chance to convert the sugar (C6H12O6) to CO2

The chemical reaction (or at least the end result of the yeast's reduction
of sugar goes like this:

C6H12O6(aq) = 2(CH3CH2OH(aq)) + 2(CO2) + energy (used by yeast)

so, for each mol of sugar you get 2 mol of CO2 and because the molar weight
of sugar is 180 g/mol and the molar weight of alcohol is 38 g/mol, you will
get (2 * 40 g/mol) / 180 g/mol = 0.4444 g CO2 for each g og sugar.

This is max you can get but because some of the CO2 will stay in the water
in the yeast reactor you will get a little less than the 0.4444 g CO2 / 1g
C6H12O6 mentioned above.


Since the molar weight for alcohol (CH3CH2OH) is 38 g/mol you will get (2 *
38 g/mol) / (180 g/mol) = 0.4222 g alcohol for each g sugar added to the
reactor.


But, because the alcohol will kill the yeast if the concentration gets to
high (depending on which type of yeast is used, common baking yeast will
start to die arround (7% - 8%) we need to make sure that the concentration
of alcohol is low enough to make sure that all the sugar is consumed before
the alcohol kills the yeast.



If using 2.0L of water (H2O) = 2000g and 220g og sugar the end concentration
will be (0.4222 * 220 g alcohol ) / (2000 g water) = 0.046444 = 4.6444 %
which will alow the yeast to consume all the sugar and still survive the
alcohol.


When all the sugar is gone the yeast will 'floculate' out of solution and
sink to the bottom of the yeast container but will not die, so we can
actually re-use the yeast every time we set up another batch of sugar if we
carefully drains the water / alcohol solution from the container and don't
rinse the container with very hot water killing the yeast in the process.

In the long run it will benefit the yeast if we used a yeast nutrient (can
be bought from home brewers shops) to feed the yeast the nutrients that the
yeast needs to stay healthy for prolonged use.


Because some of the CO2 stays in the water we have a buffer solution like
this:

CO2 + H2O = H+(aq) + HCO3-(aq)

This process is dependent on temperature and the specific wapor pressure of
CO2 in the container and the water, but i can't remember how to calculate
the exact ammount of CO2 in solition given the pressure / temperature of the
solution, so I'll ignore this bit :-)

When adding baking soda you effectively increases the kH of the solution
which loveres the pH making the environment a little more hostile to the
yeast. If i remember correctly yeast prefers a pH of 5 to 6, but will
survive 4 to 9, so there are some room for pH swings before the yeast gives
up.

This reaction goes like this:

2NaHCO3 + H2O = 2Na+(aq) + 2HCO3-(aq)


Baking soda can be added to stabilise the pH in the reactor if the water
used have a very lov Kh, but for normal (higher that 4 Kh) water baking soda
actually makes the conditions for the yeast worse but might prolong the
reaction somewhat purely because some of the yeast will die because of the
higner pH in the reactor.



I hope this came through as i thought it, if not please dont hesitate to ask
further questions :-)


Regards

Morten



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Checked by AVG anti-virus system (http://www.grisoft.com).
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  #11   Report Post  
Old 05-03-2004, 04:30 AM
Harry Muscle
 
Posts: n/a
Default DIY CO2 system question

"Morten" wrote in message
...

SNIP

The addition of baking soda (2NaHCO3) will not lower the amount of alcohol
(CH3CH2OH) on the solution unless you put so much if in there that it

lovers
the pH too much below 5 effectually killing the yeast before it gets a
chance to convert the sugar (C6H12O6) to CO2

The chemical reaction (or at least the end result of the yeast's reduction
of sugar goes like this:

C6H12O6(aq) = 2(CH3CH2OH(aq)) + 2(CO2) + energy (used by yeast)

so, for each mol of sugar you get 2 mol of CO2 and because the molar

weight
of sugar is 180 g/mol and the molar weight of alcohol is 38 g/mol, you

will
get (2 * 40 g/mol) / 180 g/mol = 0.4444 g CO2 for each g og sugar.

This is max you can get but because some of the CO2 will stay in the water
in the yeast reactor you will get a little less than the 0.4444 g CO2 / 1g
C6H12O6 mentioned above.


Since the molar weight for alcohol (CH3CH2OH) is 38 g/mol you will get (2

*
38 g/mol) / (180 g/mol) = 0.4222 g alcohol for each g sugar added to the
reactor.


But, because the alcohol will kill the yeast if the concentration gets to
high (depending on which type of yeast is used, common baking yeast will
start to die arround (7% - 8%) we need to make sure that the concentration
of alcohol is low enough to make sure that all the sugar is consumed

before
the alcohol kills the yeast.



If using 2.0L of water (H2O) = 2000g and 220g og sugar the end

concentration
will be (0.4222 * 220 g alcohol ) / (2000 g water) = 0.046444 = 4.6444 %
which will alow the yeast to consume all the sugar and still survive the
alcohol.


When all the sugar is gone the yeast will 'floculate' out of solution and
sink to the bottom of the yeast container but will not die, so we can
actually re-use the yeast every time we set up another batch of sugar if

we
carefully drains the water / alcohol solution from the container and don't
rinse the container with very ater killing the yeast in the process.

In the long run it will benefit the yeast if we used a yeast nutrient (can
be bought from home brewers shops) to feed the yeast the nutrients that

the
yeast needs to stay healthy for prolonged use.


Because some of the CO2 stays in the water we have a buffer solution like
this:

CO2 + H2O = H+(aq) + HCO3-(aq)

This process is dependent on temperature and the specific wapor pressure

of
CO2 in the container and the water, but i can't remember how to calculate
the exact ammount of CO2 in solition given the pressure / temperature of

the
solution, so I'll ignore this bit :-)

When adding baking soda you effectively increases the kH of the solution
which loveres the pH making the environment a little more hostile to the
yeast. If i remember correctly yeast prefers a pH of 5 to 6, but will
survive 4 to 9, so there are some room for pH swings before the yeast

gives
up.

This reaction goes like this:

2NaHCO3 + H2O = 2Na+(aq) + 2HCO3-(aq)


Baking soda can be added to stabilise the pH in the reactor if the water
used have a very lov Kh, but for normal (higher that 4 Kh) water baking

soda
actually makes the conditions for the yeast worse but might prolong the
reaction somewhat purely because some of the yeast will die because of the
higner pH in the reactor.



I hope this came through as i thought it, if not please dont hesitate to

ask
further questions :-)


Regards

Morten



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.611 / Virus Database: 391 - Release Date: 03/03/2004



That's a keeper. Nice explanation. Here's a link to a site that also goes
into a lot of detail about DIY CO2:
http://www.qsl.net/w2wdx/aquaria/diyco2.html . It even talks about which
yeast is best, etc. FYI, it's a long read.

Harry




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  #12   Report Post  
Old 05-03-2004, 04:30 AM
Morten
 
Posts: n/a
Default DIY CO2 system question

Hi Harry

"Harry Muscle" wrote in message
...
"Morten" wrote in message
...


That's a keeper. Nice explanation. Here's a link to a site that also

goes
into a lot of detail about DIY CO2:
http://www.qsl.net/w2wdx/aquaria/diyco2.html . It even talks about which
yeast is best, etc. FYI, it's a long read.


If only I knew before i started describing this lenghty process :-)


/Morten




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Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.611 / Virus Database: 391 - Release Date: 03/03/2004


  #13   Report Post  
Old 05-03-2004, 04:34 AM
Morten
 
Posts: n/a
Default DIY CO2 system question

Bannor,

"bannor" bannor -at- echoes - net - mind the spam block wrote in message
...
On Thu, 26 Feb 2004 21:08:55 GMT, "Ken Pinard"
wrote:

The answer to your question is depends: Is the bottle below or above
the tank? If Below, there is no way for the contents of the bottle to
get into the tank unless you knock it over. If the bottle is above
the tank, then yes, there is the possiblity.

I have mine below the tank, and also have them (I have 2), tied so
that they can not be accidentally knocked over by my curious cats.
With a one gallon jug, I doubt that it would easily be knocked over,
so I doubt that you will have that problem.

One thing you can do to help allieviate some of the alcohol is to add
baking soda to your water after you have disolved the sugar. In a one
gallon container, up to around 1/4 cup would be fine. That will
reduce the amount of free alcohol in the mix but will not stop the
conversion to co2 gas. You will still have to change the mixture out
on the same schedule though.


The addition of baking soda (2NaHCO3) will not lower the amount of alcohol
(CH3CH2OH) on the solution unless you put so much if in there that it lovers
the pH too much below 5 effectually killing the yeast before it gets a
chance to convert the sugar (C6H12O6) to CO2

The chemical reaction (or at least the end result of the yeast's reduction
of sugar goes like this:

C6H12O6(aq) = 2(CH3CH2OH(aq)) + 2(CO2) + energy (used by yeast)

so, for each mol of sugar you get 2 mol of CO2 and because the molar weight
of sugar is 180 g/mol and the molar weight of alcohol is 38 g/mol, you will
get (2 * 40 g/mol) / 180 g/mol = 0.4444 g CO2 for each g og sugar.

This is max you can get but because some of the CO2 will stay in the water
in the yeast reactor you will get a little less than the 0.4444 g CO2 / 1g
C6H12O6 mentioned above.


Since the molar weight for alcohol (CH3CH2OH) is 38 g/mol you will get (2 *
38 g/mol) / (180 g/mol) = 0.4222 g alcohol for each g sugar added to the
reactor.


But, because the alcohol will kill the yeast if the concentration gets to
high (depending on which type of yeast is used, common baking yeast will
start to die arround (7% - 8%) we need to make sure that the concentration
of alcohol is low enough to make sure that all the sugar is consumed before
the alcohol kills the yeast.



If using 2.0L of water (H2O) = 2000g and 220g og sugar the end concentration
will be (0.4222 * 220 g alcohol ) / (2000 g water) = 0.046444 = 4.6444 %
which will alow the yeast to consume all the sugar and still survive the
alcohol.


When all the sugar is gone the yeast will 'floculate' out of solution and
sink to the bottom of the yeast container but will not die, so we can
actually re-use the yeast every time we set up another batch of sugar if we
carefully drains the water / alcohol solution from the container and don't
rinse the container with very hot water killing the yeast in the process.

In the long run it will benefit the yeast if we used a yeast nutrient (can
be bought from home brewers shops) to feed the yeast the nutrients that the
yeast needs to stay healthy for prolonged use.


Because some of the CO2 stays in the water we have a buffer solution like
this:

CO2 + H2O = H+(aq) + HCO3-(aq)

This process is dependent on temperature and the specific wapor pressure of
CO2 in the container and the water, but i can't remember how to calculate
the exact ammount of CO2 in solition given the pressure / temperature of the
solution, so I'll ignore this bit :-)

When adding baking soda you effectively increases the kH of the solution
which loveres the pH making the environment a little more hostile to the
yeast. If i remember correctly yeast prefers a pH of 5 to 6, but will
survive 4 to 9, so there are some room for pH swings before the yeast gives
up.

This reaction goes like this:

2NaHCO3 + H2O = 2Na+(aq) + 2HCO3-(aq)


Baking soda can be added to stabilise the pH in the reactor if the water
used have a very lov Kh, but for normal (higher that 4 Kh) water baking soda
actually makes the conditions for the yeast worse but might prolong the
reaction somewhat purely because some of the yeast will die because of the
higner pH in the reactor.



I hope this came through as i thought it, if not please dont hesitate to ask
further questions :-)


Regards

Morten



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  #14   Report Post  
Old 05-03-2004, 04:35 AM
Harry Muscle
 
Posts: n/a
Default DIY CO2 system question

"Morten" wrote in message
...

SNIP

The addition of baking soda (2NaHCO3) will not lower the amount of alcohol
(CH3CH2OH) on the solution unless you put so much if in there that it

lovers
the pH too much below 5 effectually killing the yeast before it gets a
chance to convert the sugar (C6H12O6) to CO2

The chemical reaction (or at least the end result of the yeast's reduction
of sugar goes like this:

C6H12O6(aq) = 2(CH3CH2OH(aq)) + 2(CO2) + energy (used by yeast)

so, for each mol of sugar you get 2 mol of CO2 and because the molar

weight
of sugar is 180 g/mol and the molar weight of alcohol is 38 g/mol, you

will
get (2 * 40 g/mol) / 180 g/mol = 0.4444 g CO2 for each g og sugar.

This is max you can get but because some of the CO2 will stay in the water
in the yeast reactor you will get a little less than the 0.4444 g CO2 / 1g
C6H12O6 mentioned above.


Since the molar weight for alcohol (CH3CH2OH) is 38 g/mol you will get (2

*
38 g/mol) / (180 g/mol) = 0.4222 g alcohol for each g sugar added to the
reactor.


But, because the alcohol will kill the yeast if the concentration gets to
high (depending on which type of yeast is used, common baking yeast will
start to die arround (7% - 8%) we need to make sure that the concentration
of alcohol is low enough to make sure that all the sugar is consumed

before
the alcohol kills the yeast.



If using 2.0L of water (H2O) = 2000g and 220g og sugar the end

concentration
will be (0.4222 * 220 g alcohol ) / (2000 g water) = 0.046444 = 4.6444 %
which will alow the yeast to consume all the sugar and still survive the
alcohol.


When all the sugar is gone the yeast will 'floculate' out of solution and
sink to the bottom of the yeast container but will not die, so we can
actually re-use the yeast every time we set up another batch of sugar if

we
carefully drains the water / alcohol solution from the container and don't
rinse the container with very ater killing the yeast in the process.

In the long run it will benefit the yeast if we used a yeast nutrient (can
be bought from home brewers shops) to feed the yeast the nutrients that

the
yeast needs to stay healthy for prolonged use.


Because some of the CO2 stays in the water we have a buffer solution like
this:

CO2 + H2O = H+(aq) + HCO3-(aq)

This process is dependent on temperature and the specific wapor pressure

of
CO2 in the container and the water, but i can't remember how to calculate
the exact ammount of CO2 in solition given the pressure / temperature of

the
solution, so I'll ignore this bit :-)

When adding baking soda you effectively increases the kH of the solution
which loveres the pH making the environment a little more hostile to the
yeast. If i remember correctly yeast prefers a pH of 5 to 6, but will
survive 4 to 9, so there are some room for pH swings before the yeast

gives
up.

This reaction goes like this:

2NaHCO3 + H2O = 2Na+(aq) + 2HCO3-(aq)


Baking soda can be added to stabilise the pH in the reactor if the water
used have a very lov Kh, but for normal (higher that 4 Kh) water baking

soda
actually makes the conditions for the yeast worse but might prolong the
reaction somewhat purely because some of the yeast will die because of the
higner pH in the reactor.



I hope this came through as i thought it, if not please dont hesitate to

ask
further questions :-)


Regards

Morten



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That's a keeper. Nice explanation. Here's a link to a site that also goes
into a lot of detail about DIY CO2:
http://www.qsl.net/w2wdx/aquaria/diyco2.html . It even talks about which
yeast is best, etc. FYI, it's a long read.

Harry




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  #15   Report Post  
Old 05-03-2004, 04:35 AM
Morten
 
Posts: n/a
Default DIY CO2 system question

Hi Harry

"Harry Muscle" wrote in message
...
"Morten" wrote in message
...


That's a keeper. Nice explanation. Here's a link to a site that also

goes
into a lot of detail about DIY CO2:
http://www.qsl.net/w2wdx/aquaria/diyco2.html . It even talks about which
yeast is best, etc. FYI, it's a long read.


If only I knew before i started describing this lenghty process :-)


/Morten




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