DIY CO2 - what did I do wrong?

[marchmaxima]

Hopefully someone can tell me what I did wrong with my DIY CO2 recipe.

I put 2 cups of raw sugar, 1/2 teaspoon of baking soda and warmish water in a 2L bottle and shook it up to dissolve it.

I put 1/4 teaspoon of dry bakers yeast in a cup of tepid water, mixed it, added a pinch of sugar and whisked it up for a few mins and let it sit for 10mins. After the 10 mins had passed, it looked like the yeast was starting to bubble.

I poured this straight into the bottle of sugar-water, and hooked it up.

3 and a half hours later and I haven't seen a bubble pass through the bubble counter. At the moment, the contents of the bottle looks like flat ginger beer. It certainly doesn't look like anything is going on in there that would cause gas.

I'm pretty certain my seals are airtight. Any ideas?

 

[mackdaddy81]

I don't know if this would cause it, but maybe the yeast died during that 10 minutes because they didn't have a food source. I always fill up the whole 2 liter with tepid water, and then I add the sugar, baking soda, and yeast all at once.

 

[marchmaxima]

When I whisked it before I let it sit, I did put a few pinches of sugar in with it.

 

[fort384]

THe yeast wouldn't have died in that 10 minutes. Was there a frothy head on the yeast before you dumped it in the bottle? You should see bubbles in the bottle too if the mix is working. Shine a flash light into the side of the bottle to light it up - you should see tons of bubbles if it working. You can try painting some soapy water onto the connections using a paint or pastry brush to check connections. If it is not air tight, you won't see any bubbles coming out because the gas will leak (it will take the path of least resistance).

If the yeast was producing when you dumped it in the bottle, then my guess is you have a leak.

 

[fort384]

Sharon, something else too: I would recommend 1/8 tsp of sodium bicarbonate, and 1/2 tsp of yeast.

Sodium bicarb in excess can kill the yeast.

 

[neilanh]

3.5 hours isn't enough to get enough pressure built up in your system. It's not uncommon for it to take 24 hours. Give it at least a day before you mess with it. Every time you open the cap and depressurize the system, you start over.

Just like everything else, patience in this hobby is the key.

 

[fort384]

3.5 hours isn't enough to get enough pressure built up in your system. It's not uncommon for it to take 24 hours.

Granted, I used 1 L bottles on my system, not 2L, but I always got bubbles within about 1/2 hr of hooking up to my system.

It really depends on how much room you leave at the top of the bottle, how much tubing you have, etc. But Neil is correct that opening the system releases any pressure built up and starts you over. You should be able to see the water level in your airline tubing being pressed down towards the release point of the CO2 into water (or your gas separator) if it pressurizing...

 

[neilanh]

Understood fort, like you said every system is different. How long is the tubing from the bottles to the aquarium, how deep in the water is the outlet, what diffuser, etc etc etc, is all going to have an effect on how much pressure has to be built up before you can visibly see results.

My old 2x2L system took ~12-16 hours to produce at startup.

 

[marchmaxima]

I couldn't say it was frothing, but things were moving around. More circulating if that makes sense. Definitely no bubbles in the bottle. As I said, I looks stagnant and flat. Have not opened it since I hooked it up. Will give it 24 hours. Hopefully it might bubble by morning.

Guess I was a little confused being that most people said they got a "burst" of CO2 production pretty quickly.

 

[fort384]

If you shined a light in and saw no bubbles, I think the culprit could be too much baking soda, not enough yeast.

Even if it takes some time for your system to build up pressure (Again dependent upon how much volume the gas has to fill before it is forced out the airline), you should still see a sea of bubbles in the bottle instantly.

wow say that last part 10 times fast

I would say it should look like something akin to a bottle of opened champagne or a freshly pored beer.

 

[marchmaxima]

Thanks Fort. I'm extremely familiar with the look of a fresh beer Mine looks more like iced tea. I don't think this batch took. I think I might throw this batch and give it another go with less Bi-carb.

FYI, the generator is a 2L bottle that has a short (15cm-ish) airline into a second 600ml bottle used as a gas separator. Then there is another airline out to a bubble counter and then a line from that into the tank. That line from the gas seperator to the diffuser is around 90-100cm.

 

[fort384]

Remember too the more you fill the bottle, the less space the gas has to fill. Just don't go too full, or it will cause nasty yeast mix to creep up the air tube. Use the tepid water in the mixture to speed things along as well (but not HOT, that will kill the yeast)

 

[marchmaxima]

Okay. New mix now done and attached. I used 1/2 teapoon of yeast and a 1/8-1/4 teapoon of bi-carb (hard to tell, I don't have a 1/8th measuring spoon.

Interestingly, this time there was definitely a difference in terms of the froth that built up on top of the yeast 10-min sitting period.

We see how we go.

 

[timwag2001]

try shaking the two liter bottle.

i had problems getting bubbles for almost 2 days. first i had only put 2 cups of water in the bottle. and it sucked. then i filled it up to where the bottle started to curve. a few hours later i was in business.

 

[SWerner13]

I don't use baking soda at all and it works great I would say approximately 40-50 bubbles per minute? What does the baking soda do? or supposed to do?

 

[fort384]

The baking soda will reduce the acid content of the mix, that results from the yeast consuming the sugar. Once the acidity gets strong enough, it will kill the yeast. By adding a small amount of sodium bicarb, it will neutralize some of the acid.

Too much though, and just the opposite will happen, it will kill the yeast because the mix will be to alkaline.

 

[marchmaxima]

Update: I've gotten up this morning and I've noticed two things.

1. The bottle looked flat again. I gave it a bit of a swirl as tim_wagner suggested and it did give off some bubbles that's a good thing.

2. There is water in the bottle I use as my gas separator. It's a 600ml bottle and there would be probably a little over an inch of water in the bottom. It's coming from the airline that connects the 2L bottle and the gas seperator. There's probably 1 drop every 5-10 seconds. I assume its condensation because the water is clear, and not brown in any way. There is a check valve between the generator bottle and the gas seperator. Anyone else have this problem?

No Co2 going though the bubble counter yet. Guess I'll leave it for the day and check it again tonight.

 

[timwag2001]

another tip would be to eliminate one of the bottles. your gas seperator and your bubble counter can be one bottle.

if you shake the bottle too much it can suck some of the water out of your 2 liter. i have a shut off valve right after the 2 liter bottle.
i shut off the valve and shake the bottle vigorously and quickly open the valve and it spits out a bunch of co2

other than shaking the bottle there is really no reason for water to go from one bottle to the other unless your 2 liter is over filled.

can you take pics?

 

[An t-iasg]

I would not recommend shaking or swirling the bottle with yeast and sugar mixture already added. It's fine to shake the water and sugar mixture to dissolve the sugar, but with yeast added, a build-up of pressure could blow the cap of the bottle off and injure you somehow. Or it could send a sticky mess everywhere. Assume the bottle is under pressure even if it doesn't look like the yeast is bubbling. I once took a bottle to the sink to dump it out and I must have shaken it a bit much on the way to the sink (I went downstairs to the laundry tub since the expired mixture was a bit smelly to dump down the kitchen sink). When I opened the top, the mixture squirted a foamy jet all over the counter - and this was a mixture that had been active for 3-4 weeks. Please be careful!

 

[fort384]

Your gas separator bottle could be filled almost all the way to the top with water. That way there is less empty space to pressurize, and your system will output faster.

Based on what we have discussed, my guess is maybe the yeast you are using is either not viable, or different than bakers yeast we have in the states maybe? Is it just dry yeast in an envelope type thing, or the stuff in a jar? Also, is there a chance it is expired?