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Has anyone ever tried feeding their yeast something besides sugar? I wonder whether yeast might be a steadier CO2 source if they were fed something harder to access. Rolled oats? White rice? Do you think that the structure of these foods would moderate and prolong yeast growth? I'm thinking that it would be like the jello method, but easier.

I'm not a beer brewer, but I think brewers cook their grains before fermenting, so I wonder whether brewing is a direct analog of my idea.
 

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I can't remember the name of the chemical, but it's in molasses (not the unsulfurated type) that's supposed to feed the yeast and prolong life. You can try a search for the Nyberg method. I add a couple of tsp of brown sugar to mine. It actually seems to shorten the life span, but I get more consistant production. Instead of gradually slowing down, it pretty much quits when it's done.

I've tried regular protein powder without seeing an improvement. I had first tried some diet drink, soy based mix that I saw on clearance and did see a slight improvement with it--but haven't ever seen the stuff for sale since.

I've also heard that giving it a vitamin helps, but I'm not sure that I saw a real difference with that either.
 

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I add 1/2 a ml of NO3 & PO4 to the liter of yeast/sugar mixture.. From what I understand, yeast needs N & PO4 to build new yeast. My typical liter bottle lasts 1 month.

adding grains to the mixture instead of sugar just makes the fermentation slower that's all. Brewers usually roast the grains to release the sugars.

I was thinking.. how much CO2 is in a bottle of carbonated water.. Can't you just hook up a bottle of carbonated water?
 

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I was thinking of just hooking up a bottle of soda. Theres already 40 grams of sugar in there... and like you say some carbon dioxide. Baking soda is cheap if you need to neutralize the citric acid. I'm not really familiar enough with how yeast works to know what else you would have to do. Generic soda or sale soda is less than a dollar per 2L.
 

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Has anyone ever tried feeding their yeast something besides sugar?....
Hi swylie

The following info comes from Tarah Nyberg's Yeast CO2 powerpoint presentation from the AGA2K3 convention. http://www.aquatic-gardeners.org/Nyberg_yeast.ppt

It answers some of your questions, swylie. I hope it helps you. It goes back to what spypet and CherylH mentioned

How to live on the cheap --CO2
I have used yeast CO2 on tanks up to 180 gal. Also 75s, 65s etc.
2 gallons of yeast changed once every 3wks to month depending on the temperature works well. I don’t rotate the bottles either.
The key to long lasting cultures is allowing them to grow and be happy. Also a little basic knowledge of yeast growth helps.

Yeast Growth/metabolism
Yeast can either produce energy by fermentation or oxidative phosphorylation (ox/phos)
Yeast greatly prefer fermentation over ox/phos and will not start ox/phos until all the sugars are converted to ethanol.
Ethanol is a good source of energy and in the presence of oxygen yeast use it up as well.
Fermentation also produces 2 CO2 molecules per molecule of sugar-- as a by product. =)

Why is just sugar and water not ideal?
When you just add sugar and water to yeast, they are essentially starving to death.
However the enzymes for converting sugar to ethanol are still in the cell and will work for a limited amount of time.
Since the cells do not have what they need to make new enzymes as cells starve/run out of enzymes the culture produces less and less CO2.

Also, we add too much sugar.
Ethanol and sugar are increasingly toxic to yeast at greater than 10% concentrations.
Therefore 2cups (~500ml) of sugar in 2L of water (~25% sugar) is unhealthy for the yeast.
It is also a waste of sugar because 10% sugar will yield roughly 10% Ethanol at which point the yeast stop growing anyway.
Special strains of yeast, like champaine and wine yeast, have stronger cell walls that protect them from the Ethanol -- so they grow longer.

Happy yeast give you long, productive cultures.
The solution is to give yeast less sugar and also supply them with the nutrients they need to grow.
This will give you a long lived culture that produces a consistent amount of CO2, (they are not challenged by toxic conditions at the beginning and end)
Also your yeast mass at the end will be alive and well and able to quickly start growing again when you add more sugar.

The Recipe!
Improvise at will, but here is a good start:
Use 1 cup sugar per 2L H20 (tank water is great or dechlorinated tap -- chlorine, but not ammonia, kill yeast. ) (they like ammonia)
Add 1-2 tsp of a protein drink mix
(optional) Add 1 tsp of ammonium sulfate, otherwise use 1 T mollasses. (or both)
1 tsp baking soda is also nice to keep the pH from crashing (they like it >pH3-4)
Leave yeast from previous mix in the bottom.

Benefits/conclusons
Growing yeast this way saves you time (less re-starting) and money on sugar and yeast.
The only real extra cost is the protein mix, but you can use really old/cheap stuff.
The key thing is that it has protein and vitamin/minerals, Anything that has “yeast extract” in it is perfect.
(Even non-fat powdered milk will do the trick, but it will smell funny)
 

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I was thinking of just hooking up a bottle of soda. Theres already 40 grams of sugar in there... and like you say some carbon dioxide. Baking soda is cheap if you need to neutralize the citric acid. I'm not really familiar enough with how yeast works to know what else you would have to do. Generic soda or sale soda is less than a dollar per 2L.
39 grams per 350mL can. :D That's about 223 grams of sugar in a 2L bottle! :eek5:
 
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