# Yeast for DIY Co2 System



## nagukush (Mar 13, 2008)

Friends, just wanted some guidance on the yeast to be used with the DIY System. Actually I can get 3 types of yeasts here-

1. The normal Brownish colored Speheres that come in boxes from common stores










2. A Baker here has these small white colored granules










3. A Yeast Paste that I recently got from another baker. He said that it works instantly. I've used this for my current DIY Co2 but it doesnt seem very efficient...

Which of the above is best suitable for our DIY System ? Kindly guide me...
Thanks a lot !
Kush


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## starrystarstarr (Dec 18, 2008)

i have always used the fast acting yeast you get in the baking isle at the super market


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## robinnight (Feb 3, 2009)

Wine yeast is best. But I use what's at the supermarket.


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## PaulNorth (Jan 17, 2009)

robinnight said:


> Wine yeast is best. But I use what's at the supermarket.


I posted something about this on TPT - don't know if anyone has thought about this much. Total stab in the dark, because I'm not sure how one would operationalize the vague concept, but just a thought:

All yeasts have an aerobic phase, when they respire and undergo propagation (budding "daughter cells") to the optimal population density, given the solution environment they find themselves in (amount and structure of sugars in solution, etc.); then they undergo anaerobic fermentation.

A high pitching rate and higher temperature tends to increase the rate of fermentation, and shorten the length of fermentation - for example, most brewers consider a 6X -10x yeast replication optimal for brewing purposes - pitch too little, and the tendency is for a good many off-compounds to kick out as the yeast struggles to reach its proper population density; overpitch, very little aerobic respiration takes place, and this can cause its own problems down the road - one of which is the _absence_ of some desired fermentation components, such as the esters of a good many ales.

Anyway, all yeasts have a non-linear fermentation profile - depending on pitching rate and temp, a lag time during respiration, a buildup to a maximal CO2 and ETOH synthesis from sugars, and a slowdown as yeast metabolism slows down and yeast dies off due to the presence of ETOH and absence of available sugar in solution (they undergoe "autolysis," or self-consumption, in attempting to "keep eating.")

Ale yeasts, typical _saccharomyces cerevisae_, tend to higher rates, and a more rapid buildup and slowdown. In my brewing practice, which includes O2 injection and other things to encourage optimal yeast health, fermentation is fast, furious, and typically over within 4-5 days.

Lager yeasts (var. of _saccharomyces carlsbergensis_), however, tend to a slower, more even ferment. Because of this, I would think, if you're doing DIY CO2, that it might be easier to dial in a more steady rate of production with lager "brewing" than when using ale yeasts. Just a thought (as I inject CO2), but has anyone thought to DIY lager yeast, in a fridge, with lines out to the tank?


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## Reginald2 (Feb 8, 2009)

PaulNorth, that is really interesting. I don't have any brewing experience, but I do enjoy baking bread. It sounds like temperature and exposure to air might be some commonalities that we don't take into account in our DIY CO2. 

When I bake bread, ideally the temperature will be around 85 - 90 (I don't know if that identifies the yeast strain that Fleischmann uses). I suppose it may be a little more complicated because, in baking the dough forming proteins and gluten is equally as important as fermentation.

Consistent temperature is something to be sought after for a good, even rise. Likewise, I don't want wild fluctuations in my aquarium CO2. However, over the course of the day the temperatures in my apartment probably vary by 10-15 degrees. Confusing my yeast and altering my CO2 output.

I once saw a post (I am sorry I don’t remember where) in which someone talked about using a heating pad to speed CO2 production. One morning, when it was cool in my apartment, I gave it a go. Sure enough, in a few minutes I could see the bubble rate increasing. I wish I could remember where I saw that post; I think that person was on to something. A heating pad makes me nervous though, and mine cuts off after a few minutes anyway.

You also mentioned aerobic multiplication. This is another similarity in beer and bread making. About halfway through the rise, I will give the dough a little extra kneading to reintroduce oxygen into the mix to help speed the process along. Due to one way valves and aquariums this doesn’t seem to have quite the same parallels; but I have been known to give the ‘ole two liter a shaking every now and then.

I wonder if anyone has attempted to create a real stable environment for a DIY CO2 generator, like tossing it in a sump. In a similar vein, I wonder if there has been much experimentation with how long the yeast concoction is exposed to oxygen before it is stuck in the anaerobic conditions of our generators.

Interesting post, thanks.

P.S. Kush That first picture looks like what I use. The dry yeast, it takes a little while to start working. If you want to speed that process up you can dissolve it in warm water with some sugar.


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