|01-29-2013 05:22 PM|
|01-29-2013 04:26 PM|
|uberape||brown sugar, champagne yeast and a pinch of baking soda in initially warm water works the best. slow to get going and sometimes an extra later shake is required but it lasts twice as long and is far more regular than white sugar with bread yeast. the only problem is champagne yeast is a whopping 75p more expensive and brown sugar 25p more. check with your accountant before you make the switch.|
|01-29-2013 10:05 AM|
That is absolutely brilliant. Simple.
|01-29-2013 08:23 AM|
We don't need the airstones, just those clear plastic adapters inside. A cross sectional view of what I described:
Shoving that adapter hard into the tubing expands it a lot more securely against the edges of the hole, than just pulling tubing through a slightly undersized hole. The finished product:
|01-29-2013 03:01 AM|
|01-28-2013 05:06 PM|
I just use the put everything in the bottle and shake method, works fine for me. When I change bottles I usually make the replacement bottle a couple days ahead to give the reaction time to stabilize.
I've tried the non glue method, but there was always some small leak somewhere that made keeping a constant pressure a little difficult. Lots of hot glue and the plastic air line connectors have done the trick for me.
|01-28-2013 05:01 PM|
|01-28-2013 04:00 PM|
Just to demonstrate how non-sensitive DIY CO2 is to specific techniques:
If we were to keep the bottles upside down, of course with the CO2 tube long enough to reach the bottom of the bottle, that would eliminate any CO2 leakage at the bottle cap connections. The tiny amount of leak of the solution shouldn't be a problem. (just think about this for awhile!)
|01-28-2013 04:21 AM|
I wouldn't sweat the 120 F thing too much- it's more to help the sugar dissolve than anything to do with aseptic technique. Among other things, the vessel isn't sterile, the inoculum isn't pure, and 120 F isn't going to do much for getting rid of bacteria or mold in any case.
In order to minimize the chance of mold contaminants, just work quickly and minimize the time you have the bottle opening pointed upward toward the open air and the amount of time the sugar/buffer mixture sits out. Mold is probably the one thing you should worry about, especially in humid environments.
While alcohol is definitely an issue toward the end of the fermentation run, weak organic acid build up and changes in osmolarity are just as much of a problem for the yeast. As others have mentioned in their recipes, try a little baking soda and a pinch of salt.
Laying the bottle on its side will help with gas exchange, as will not overfilling it. Try to shoot for no more than 1/2 full, 1/3 full if you keep the bottle vertical instead of tipped horizontally.
Don't even bother washing out the old bottle or changing the culture as long as its healthy. Just dump out most of the old liquid and pour in the new stuff. If you leave some residue in the bottom of the bottle, there will be plenty of yeast left.
As for the bottles, I shrink the gas separator bottle down to thicken the plastic. If your dishwasher has a sanitize option, that should be enough to shrink it. I'm currently using a shrunken 12 oz Dr. Pepper bottle for that and a Schweppes Ginger Ale bottle for the fermentation vessel. The walls on the latter are thicker. For connectors, I'm using Foremost bulkhead fittings sealed with GE silicone caulk (the kind without the mildew inhibitors, as the chemicals GE uses work on yeast too). The bottles themselves sit in a plastic tub lined with old hand towels to absorb the gunk if and when there's some sort of catastrophic failure. I used to work with organisms that grew optimally at 30 atmospheres of pressure and 105C, so I'm probably overly paranoid in that regard.
|01-28-2013 03:34 AM|
Just wanted to add that using a hot screwdriver tip or soldering iron to make a hole with a 1/16 to 1/8" smaller diameter than tubing creates a better seal
|01-26-2013 08:11 PM|
One question: Why fast rise yeast instead of standard? I've never tried it but have been warned off it, saying it will give a sharper peak in production.
And comments: Always remember, we're not making bread here. If bread fails to rise within the expected time, you have a disaster. If DIY CO2 takes an extra hour or two to start producing, no big deal. If you kill some of the yeast, probably also no big deal. I bought a bottle of "yeast nutrient" once at someone's recommendation, then read the label - seems it's just dead yeast, which the live yeast feed off of to make more live yeast. No wonder we often get away with chlorinated water, non-optimal temperatures, lack of "proofing", old yeast, etc.
I just put sugar, yeast, and baking soda in the bottle, add lukewarm water, shake the dickens out of it, and away it goes. The time to start varies, but is otherwise reliable as clockwork. Only two yeast failures - one when I tried skipping the shake, and the other when I tried a really tiny amount of yeast.
I think the majority of failures are due to two things.
Temperature extremes is one. Some people apparently think 120°F is lukewarm. I consider this evidence for aliens masquerading as humans on Earth. If I'm wrong, and these folks aren't aliens, I pray they never need to warm a baby bottle.
And leaks, which I've had more of. No glue or caulk adheres well to polyethylene (bottle caps), and only slightly better to vinyl, so better to use glueless methods. And don't swap caps. For example, I tried swapping a Mountain Dew cap onto a Diet Coke bottle, because I decided I wanted a clear bottle instead of green, and the Dew cap was already drilled. It looked compatible, and felt right going on, but absolutely would not seal.
|01-26-2013 07:24 PM|
I add a pinch of KH2PO4 for some minerals, just in case the yeast needs a bit more than sugar.
1 c white granulated sugar
1 qt. water
1/8 tsp per yeast
TINY pinch of KH2PO4
I make a big batch all at once in a production line:
1) Yeast in tap-hot water (water heater is set at 110*F). Stir gently a few times as the yeast dissolves.
2) Heat about half the water on the stove, turn off heat. Stir in sugar until it dissolves. Water is cooling off, too. Add only a generous pinch of KH2PO4 to the whole batch.
3) Put less than half the water (cold) into all the bottles.
4) Pour in the hot sugar water. It is not so hot to cause problems with the plastic bottles, and pouring it into the cold water cools it off even more, so it is not too hot for the yeast.
5) Add yeast.
6) Use remaining water to top off any bottles. I also use it to rinse the pot the sugar water was in, and the yeast bowl so that all the ingredients end up in the bottles.
All bottles (most are 2 liter) are filled to the bottom of the shoulder or the top of the label (if the label remains)
Swirl gently, do not get the mixture into the cap or the tubing.
Production is about what others are showing: About 24 hours or less to ramp up, a week of good production, another week of so-so production, then a week of trailing off. I find during that last week if I gently swirl the bottle each morning the production is a bit better, but it does not last.
I sit the bottles on top of or near the lights, on top of the tank. Heat during the day (lights on) might make the yeast grow better, cooler at night. I know, timing is all wrong. Need to heat it several hours before lights on.
|01-26-2013 05:28 PM|
I have done something close to experimenting when I first started diy co2.
here are my results.
all batches are in 2 liter bottles. and shaken up.
1/4 tsp yeast
no baking soda
results: 3 weeks of co2, first week about 2-4 bps, second week 1-3 bps, and third week stuggles to get 1 bps
2 cups sugar
1/4 tsp yeast
no baking soda
results: first week 3-5 bps, second week 1-2, and third week struggles
1 cup sugar
1/2 tsp yeast
results: first week 3-5 bps, second week struggles towards end
2 c sugar
1/2 tsp yeast
results: first week 5+ bps, second week starts at 1-2 bps, and by the end of week all done
results with baking soda:
all results made the reaction occur faster, more stable, and slightly longer.
all baking soda tests where done with 1/2 tsp baking soda, which if my math is correct makes the water approx. 40 dkh, unable to test ph of solution on all tests.
all experiments need to be recreated by a second or third source to confirm my results. I have since settled on 1c sugar 1/4 tsp yeast and 1/2 tsp baking soda
I have heard that you could use baking powder but am unsure on this.
|01-26-2013 03:26 PM|
I add baking soda because so many others do, and the first time I tried it I had good production for about 3 weeks, so I didn't want to change anything. The same is true for my using 1 cup of sugar per liter of water. I find sugar pretty cheap, so saving half the cost of it doesn't do much for me if I think it might reduce the life of my CO2 production.
Doing hobbyist research is enjoyable. And, it can add a lot to everyone's knowledge. Someone could do some experimenting with the amount of sugar per liter, the amount of yeast per liter, the shake it or don't shake it method, how much baking soda per liter, etc. to find what seems to be the best in terms of quantity of CO2 and how long that production continues. It would take getting several 1 or 2 liter bottles set up, with bubble counters, so you could run tests with everything else the same, but different amounts of sugar, etc. Does someone want to volunteer?
|01-26-2013 02:52 PM|
|stlouisan||from what I've read in the past, people add baking soda to buffer the acidity of the alcohol when it builds up. I personally don't use it.|
|This thread has more than 15 replies. Click here to review the whole thread.|