D.I.Y. Yeast Based CO2
Here are some hints if you are going to go with a DIY yeast based CO2 system.
* Use juice bottles and not soda bottles. Bigger caps, larger openings, more stable.
* Drill a hole in the cap smaller than the OD of the tubing. Cut the tubing at an angle. Pull it though with pliers. Done. The seal is gas tight.
* Get a Hagen bubble counter/diffuser. Just that part. You don't need/want the rest. Use their tubing. It works fine.
* Use plain old white sugar. I prefer to use wine yeast because it works at the lower winter temperatures I keep the house and it has a much higher alcohol tolerance than bread yeast. And $1 will buy a year's supply. Also when recharging the bottles I pour off the liquid and use the bottle sludge for the next bottle. That's the yeast.
Have you seen Tara Nyberg's PowerPoint presentation about yeast for aquarium use?
If you have Powerpoint, you can view the whole presentation. If you don't, it is below this. Here
is the PDF only.
What are the major expenses?
Tank and stand
How to live on the cheap.
Tanks and Stand
-- buy used and pay no more than $1-2 per gallon. Re-paint stand as needed. Hammer in a few boards to make it more sturdy/look better
-- use 48” electronic T8 fixtures that you can get at the hard ware store for ~$20
How to live on the cheap- substrate
-- buy plain gravel or sand (also from hard ware store esp. if you can get the no-salt sand for icy roads)
Supplement in moderation with things like peat/soil (~1cup/ square foot) ironite (~1 T/square foot),
I like to make clay balls with added nutrients and add them both before and after a tank is planted. I recently set up a tank with nothing but clay balls. And plain gravel
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 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.
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.
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)