Hi all, I mixed up a batch of sugary yeastwater for my DIY CO2 system earlier today, and so far, it's not really done much of anything... i did 2 cups water, 1 1/2 cups sugar, and 1/4 tsp yeast... I let the yeast rise a bit in some warm water with sugar, definitely still active, i use it to make bread all the time... What's going on? Does it usually take this long to pressure up? No leaks, I checked with soap water...

It can take up to 24 hours to start producing bubbles. Do you have a bubble counter? If yes, it will start producing bubbles before you see anything come through a diffuser, if you have one. If not, you just need to wait and see. Either way, give it 24 hours before you decide whether it's working.

I have a check valve glued to a syringe with some water in it as a bubble counter and not a single thing has gone through it... i might've made a mistake in squeezing the bottle a bit to see if the check valve was working properly, and now the bottle is kinda caved in lol... I guess I'll see how it's doing tomorrow.

Yes, definately just wait longer. It took mine overnight to look like it was doing anything at all.

Yep with your mixture, its gonna take over 24hours even.

I used to have 3 bottles of CO2 mixture. About 12 hour later only I start seeing bubbles.
And this is because I used the ceramic and glass diffuser. It takes a lot of gas pressure to start bubbling.

Thank you both, I'll check it in the morning

it's also possible that there's a leak in the seal between the bottle cap and the airline tubing

although this doesn't help your problem, i believe you forgot to add the baking soda.

Try cheap rubber stoppers on your bottles as well for sure seals. And if your yeast was already activated prior to addition, it should NOT take as long as it has - the fact that your squeezed bottle remains collapsed indicates no gas is being produced. Perhaps you didn't dechlor the water you used, as chlorine will also affect the yeast?

The bottles in this thread have but 4 tablespoons of sugar and a quarter-teaspoon of baking yeast each in a half-gallon of water. A cup-and-a-half of sugar in two cups of water is more syrup than "wine" and may be part of the problem...

+1 to this:

I use the same amount of sugar, but enough water to fill a 2L bottle to within 3" of the top; which I'd estimate is at least 6 cups.

The only time I had a failure was when I skipped shaking the mix to dissolve the sugar. Instead of the sugar dissolving slowly on its own (which is what I'd hoped), it just formed a syrupy sludge at the bottom. Which, with only 2 cups of water, is what you likely have too.

In addition, 1/4 tsp. of standard-rise bread yeast is a small amount. Sugar water contains lots of energy, but almost no other nutrients needed for yeast to live. The nutrients come mainly from the yeast itself, and are recycled as older yeast die off. But I've heard there's a minimum amount of yeast that must be used for this recycling process to work, otherwise the mixture will "stall" as nutrients are too limited, and don't become available for recycling fast enough. For 1.5 cups of sugar and ~6 cups of water, I think I've gone as low as 1/2 tsp. of yeast, but usually 3/4-1 tsp.

The bottles in the thread I referred are set up for "quick burst" production, not long-term. The bottles are rotated through a daily refresh, so that each produces the initial "fizz" initially common to yeast mixtures. The heaviest production usually occurs in the first 5 - 7 days, tapering off in a pronounced slope. That leaves one each bottle always at the various stages of output and the overall quantity of gas produced at a fairly constant rate.

The problem with adding too much sugar to a long-term bottle lies not only in the lack of proper nutrients, but the produced alcohol content as well. Once the level particular to the variety of yeast is reached, production essentially stops as yeast cells die or go dormant (in combination) and all the left-over sugar simply sweetens the by-product. Alcohol, like nitrogen to fish, is a toxic waste product with the yeast.

If you want a long-term arrangement, it's best to use something other than baking yeast, and champaigne yeast is usually readily available in most areas at some of the small, DIY shops for brewing. When you refresh the bottle at the end of a production run, just carefully decant the settled bottle, leaving the dead/dormant yeast cell layer as intact as possible. Then, when the liquid is added shake well to distribute everything. In this way, and with a fair amount of caution toward cleanliness applied, you don't normally have to re-establish the colony with fresh yeast and can go through several cycles until a few other "nasties" finally make their way into the mix and it starts producing vinegar instead of alcohol...

Jaafaman,

Seems like unnecessary extra work.

I get complete fermentation of 1.25 cups of sugar in a 2L bottle, lasting 11 days at an acceptably stable rate before it drops off sharply, due to the sugar being exhausted.

I usually go with 1.5 cups instead, which gives me an extra day or two of usable production. Plus a longer taper after that as the alcohol builds to toxicity, which is still enough to avoid problems if I am late in changing a bottle.

All this with standard baker's yeast.

So why would you artificially limit your bottle lifetime to far less than what the yeast is capable of by only adding 1/4 cup of sugar? Especially in an already labor-intensive four bottle setup? You could be changing a bottle every three or four days, instead of every day. Or less if you went with some 1G bottles which would be more appropriate for this setup. Running a 75G on DIY is masochistic enough, without deliberately making it worse.

Hey guys, just thought I'd say my bottle is happily pumping out just over 1 good sized bubble per second right now - whee! We'll see how long that lasts. I'll try a different recipe next time if this one doesn't work out too well.



the airstone kinda sucks though... we'll see how it does when i hook it to the powerhead

Now, all you have to do in the future is decant off the liquid(leaving the yeast cake behind) then add a new solution of sugar water and it will restart very quickly. People waste a lot of money on yeast hear, not understanding how yeast works at all. The fermentation might be over, but I bet my dollar you can restart the yeast with new sugar water.

Instead of wasting money on "yeast nutrient" just take some old stale yeast from the fridge and put it in boiling water to kill it, mix your sugar in, and the yeast will have plenty of yummies to eat.

This isn't necessary when restarting using the same yeast cake over and over, though.

Well, that depends on your definition of "work". While the daily, two-minute routine may seem a chore to some, to me it beats cleaning horse stalls on a daily basis. And it gets me to the tank every morning in order to check things out regularly.

I already mentioned that this design's intent is high-volume production on a stable basis, but all of that is ancillary to the intended purpose of the post - to compare a bottle's reaction time with far less yeast and sugar to the OP's setup and possibly resolve the problem within. For me to expend much, if any, more time into the "whys" and "wherefores" of my own habits in response to someone else's questions amount to outright hijacking of the poster's thread. And most of what I've written in subsequent follow-ups hasn't been in response to the OP's problem, so we're probably already in danger of trodding all over the thread...