do the homemade co2 (yeast/sugar in water shaken up) work well? what doses would you use for a 12 fl oz bottle?
is this too risky of getting mold to try?
NewGrowth i hope you don't mind if i try to give motif some info on the yeast co2 method, i have a lot of experience using them to supplement co2 for my aquariums and have a very long-lasting and very productive recipe. However i cannot comment on whether or not it will be enough to maintain the optimum levels of co2 (which i think is 1200- 1500 ppm co2 but don't quote me on that) as i have never tried it or have the equipment to measure it. But if i were ever going to try to supplement co2 with a yeast co2 reactor this is the recipe i would use.
Ok motif, the formula that i use was developed to be long lasting and produce alot of co2 by Tarah Nyberg. If you search "Nyberg, yeast, co2" in google you will find quite a few hits. The first of which is a powerpoint presentation explaining about yeast and how the process works and etc. Its a short read and very informative.
Here is her recipe:
Improvise at will, but here is a good start:
2 tblsp yeast
Use 1 cup sugar per 2L luke warm 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.
I used everything that was in that recipe and it worked great, i made a few adjustments and it worked even better for me. Originally i only used yeast, sugar and water but with the addition of the ammonium sulfate (syrup) and protein mix the longevity of the recipe and quantity of co2 doubled. With just the basic formula the co2 production would last about 2 weeks, and had a very bell curve production rate meaning slow to start, peak at the middle, slowly falls to nothing. This was not good for aquarium use as it is important to maintain consistent water parameters or you can stress out and harm your fish. The Nyberg recipe on the other hand starts out fast in production and then plateaus as the cultures of yeast are being kept very healthy, then it tapers off slowly and quickly ends. This was much better as the amount and production of co2 was more consistent.
I tried adjusting the recipe every so often and found that 2 cups of sugar for 2L of water lasted about 3-4 weeks. Another thing to take account for is preparing the yeast before you add it to the mixture.
This is a very much over looked practice but pays off greatly when done properly. I used regular bakers yeast that you find at the grocery store in the baking aisle. I happened to come across two kinds from red star i think one was regular yeast, and the other was highly active. I chose the highly active of course and it was the better choice. The yeast is dry when you buy it so it needs to be rehydrated to start the process of making co2. This being said most just pour the yeast into the mixture shake it up and let it go. When i did this i waited a full 12 hours before i saw my first bubble of co2 in the bottle. This was because by adding them straight to the mixture you end killing off a large portion of the yeast.
What i do to ensure that more of the yeast bacteria survive the journey into the sugar mixture is add the 2 tblsp of yeast to a small glass of luke warm water with sugar. I then oxygenate the water through aeration by whisking it with a fork. This essentially wakes up the yeast bacteria and rehydrates them. I do this for about 5-10 mins stirring off and on making sure i'm creating bubbles as that ensures i am causing enough turbulence to cause a gas exchange to occur. I then add the yeast mixture to the sugar mixture and give it a little shake. When i did this i usually saw the first bubbles of co2 in 30 mins to an hour.
Some other things that i did to improve the whole process:
attribute for the yeast mixture when creating the sugar mixture. I over flowed the bottle once and learned my lesson.
A good funnel is a god-send.
Adding a second bottle to function as a bubble counter to i could have at least some gauge of what was being produced was helpful. Basically it was yeast bottle outlet to bubble counter bottle, bubble counter has its own outlet. The outlet from the yeast bottle is inserted into the bubble counter bottle so that it is near the bottom of the bottle and then the outlet from the bubble counter was inserted just barely into the cap of the bottle. The bubble counter bottle is then filled with water. The co2 then bubbles up through the water and out of the shorter outlet hose. This also functions as a check valve for the yeast bottle as it sometimes can leak out a bubbly goo.
Ummm the vitamin water bottles in 12 fl oz and 32 fl oz worked well as the bubble counter bottle and yeast bottle respectively. 32 fl oz is one liter so just cut the recipe in half.
When making the holes in the caps of the bottles to insert the airline hose i used an awe, a screwdriver that come to a sharp point. It goes through the plastic caps easily when twisted and forced through with pressure and doesn't crack them. This allows you to not have to use a power drill or some other means. Also make sure the hole that you make in the cap is smaller in diameter than the airline hose you use so when you thread the hose through it forms a pressure seal and eliminates the need for bulkhead fittings or sealants.
When threading the hose through the small holes in the caps it helps to cut the air line hose to have a point. You can then shove quite a bit of the point through the small hole and use pliers to pull it the rest of the way through.
Keep a spare cap that fits on your yeast bottle because you can't very well shake up the mixture with the air line outlet cap when you make the following batches. It saves you from getting a sticky hand when you realize thats the only way you're going to be able to cap the bottle to shake it.
keep your yeast cold it will last longer
Last but not least you'll eventually realize that its a bitch to have to change and mix all that crap up and replace it every three weeks and will spring for a nice co2 tank and regulator with a solenoid valve that hooks up to a co2 meter. Thats what i ended up doing at least well actually i still went on the cheaper side and started using a 20 oz paintball tank ($16 on ebay) and a paintball regulator, and needle valve combo ($34.99 from thatfishplace.com). A solenoid valve and meter would be really nice though
. Let me know if you have any questions, i hope i didn't step on your toes here NewGrowth.
Huh, Thats well under 1kg of nutrients wonder what the rest of the 1 kg is?
I just know the basics from College chemistry courses which I hated 
. 
. Thanks again!
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