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So I rigged up my second co2 reactor a few days ago and still have not witnessed any bubbles coming from the air stone.
I remember the first one I rigged up took over a day to put bubbles out and the first bubbles I saw where about a minute apart.

I used the same bottle and recipe as before
* 1 Liter Fiji water bottle
* Half full of hot h2o (apx 500 ml)
* 1 cup sugar
* 1 tsp baking soda (essentially sodium bicarbonate)
-wait for solution to dissolve and to cool to room temperature
* 1/4 tsp active yeast
*fill to taper point with cold h2o

The yeast packet had been in the butter drawer on the door of the refrigerator for a few weeks (since I opened it to mix the last batch).

It might have become inactive/ died.
:confused: How long in such a condition can yeast survive?

In the first day I saw bubbles in the water bottle.
When I completely open the pressure regulator to the point where the valve is removed I can hear a small short burst of air escape.
:confused: Is this an indication of the chemical reaction producing co2?

I do this daily when I have not witnessed any bubbles as I fear that if the solution could be reacting but cannot make through the entire process of the air line
[air line tubing > flow valve > tube > pressure regulator > air line tubing with minor points of constriction due to suction cup grips > air stone ]
and as such that it may build up excess pressure in the bottle and explode.

The bottle sits in the 5 cm space between the rear of my Aquarium and the wall.
:confused: Could a co2 reactor explosion have enough force in the horizontal plane to damage or breach the glass of the fish tank? :surprise:

:confused: If my yeast is indeed dead can I just open a new packet of Yeast and add another 1/4th tsp?

I am between jobs due to some insurance coverage b.s.(don't get me started :angryfire)and flat broke. I can't afford to buy more sugar until next month.

I should add that the yeast was just kept its packet with the open part folded over, it was not in an air tight container.

11,721 Posts
It should start reacting just about as fast as the other one, if all conditions were the same (same recipe, same temperatures).

When you say 'hot' water, how hot? Should be stated on the label, but I think 100 deg. F or 38 deg C is the goal- barely warmer than skin temperature. Too hot kills the yeast.

Yes, it could have died in the fridge in that time.

4,032 Posts
It really throws me when the weather changes, as I tend to just feel the temp with my hand.
Doesn't work all that well when you are used to do it at 30 plus degrees one week, and tens the next.
If it is too cold, it will take a bit longer to get going. When it seems output is getting low, it is usually because of a leak, check joints with soapy water.
Too hot water will just kill the yeast. I think I have been using the same yeast packet of almost 3 months now, I don't even fold it over.

If for some reason the yeast only works for a few days, I add maybe another quarter teaspoon full to the bottle. My last bottle has been up for two weeks, with no intervention.

18 Posts
Discussion Starter · #4 ·
Thanks for the info!
The recipe I used did not state the water temp so I just winged it.
I'll have to find my cooking thermometer.

I'll test the connections.
If it is dead Can I just add new yeast to the solution? Instead of dumping the whole thing and starting over.
Or is there a reason that would be the wrong thing to do?

218 Posts
There might be other factors contributing to your issues:

- If the air stone is clogged, its going to take more pressure for bubbles to be released, causing issues in a DIY set up.
- Opening the gauge minimizes pressure, and sometimes it can take a full day for pressure to build in a DIY set up, especially one bottle.
- 1tsp yeast means you will have LOTS of yeast activity for a few days, and then it will die. 1/4 - 1/2 tsp will result in less co2 produced but for 1-2 weeks at least.
- if your water is high in chlorine, this could kill the yeast (as well as the hot water). use a bit of dechlorinator to keep the tap water safe.
- if you add in the yeast together without prior mixing, it can stick to itself and die. I mix my yeast in a shot glass with sugar water until its foamy, then add it to the bottle and shake.

If you're working with somewhat expired yeast, all these issues will present even more, so it might be a frustrating mix of a bunch of things.

chances are, your bottle is not going to explode. soda bottles can withstand a TON of psi. I have a two bottle set up and i shut the co2 off at night, which means its building in the bottles at full pressure until i release it in the morning. i've never seen it get above 4 psi, and i think its 200 when the bottles can explode.

The issue with adding more yeast to the mix is that you don't know if a.) you added too much yeast and its eaten up the sugar & died or b.) if the yeast actually IS dead and is just not producing.

If its the prior, adding more yeast will be a waste since there wont be enough sugar for it to consume to create co2.

Your best bet is to slam down $4-8 and buy a small jar of active bread yeast at your local grocery store instead of the packets. It's worth it if you plan on having a DIY set up in the long run. =)
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