DIY CO2 (splokes co2 Article)

[Bk718]

I have been running diy co2 for a few months now without any issues at all, got great plant growth and Zero fish problems.. Though like everybody, Ive been trying to improve the time the mix lasts and this is where my question/suggestion comes in..

According to splokes article on CO2 basics he states

"Yeast goes through 2 basic stages – aerobic and anaerobic. In the first stage, the yeast is in aerobic mode; when there is dissolved oxygen in the solution, the yeast will use this to multiply. Yeast needs oxygen to synthesize sterols, which are used in building cell walls. Without oxygen, their ability to do this is drastically reduced; therefore, the majority of their energy is then put into metabolizing glucose. When yeast is aerobic, they actually produce more CO2 than when they are anaerobic – twice as much, in fact. However, there is no practical way for us to keep the yeast in aerobic mode and still harvest the CO2. Once all the oxygen is used up, they enter anaerobic mode, where they start to consume sugars and release ethanol and CO2 as byproducts."

Since yeast gives a greater output of co2 in its aerobic stage why not try and somehow add oxygen to the mix. My suggestion is running another line into the bottle that contains the mix with a very pourus airstone attached at the bottom. Connect the other end to an air pump, get a control valve for the pump so that it only releases a few bubbles at a time. That way the mix has an extended amount of o2 to consume therefore it stays in the aerobic stage for a longer period of time, therefore giving off more co2. I understand that this will release both co2 and o2 into the tank, but if both can be dissolved would that benefit the tank at all?? How would this affect the yeasts consumption of sugar and ethanol release??

 

[NeonFlux]

Interesting idea BK. Maybe it will work? Try it out for yourself.

 

[Sploke]

Yeah I had thought about that when I was researching the article. First off, CO2 is heavier than both air and O2 gas, so I would expect the CO2 to settle in the bottle and the oxygen would get released first. That wouldn't be a problem, I think it might take a little longer to get enough gas volume in the bottle to push the CO2 out, but I'm not sure on that one. The second part you mentioned is that you will then be putting both the CO2 and the O2 or air into the tank. I'm not sure how much air you'd need to bubble into the CO2 mix to keep it oxygenated enough to keep the yeast aerobic. I'd just think you'd end up basically having an airstone in your tank that would end up bubbling off any gain you'd get from increased CO2. Thats why I said it probably wouldn't be practical to be able to recover the additional CO2. But if you set something up to try it, I'm definitely interested in the results.

 

[Bk718]

Thanks sploke for the comment.
Though when they say dont use airstone in the tank since it will gas off any co2 in the tank im sure they mean that it will create surface disturbance/agitation which will in return gas off the co2. Here the airstone is in the mix (in the actual liquid at the bottom of the bottle) so all it will be doing is slowly releasing tiny bubbles of o2 which by the time they reach the surface of the bottle, some will be diffused in the mix.
Then like you said o2 is lighter so it will be first to exit the bottle but eventually co2 will build up and both will be released into the tank. Both will be diffused in the tank water (reach for that 100% diffusion rate) and since CO2 and O2 levels are not dependent one would still have a good % of CO2 in the tank.

I dont know lol maybe im just confusing myself here or just missing something.. But hey thats what you guys are here for, to throw in your 2 cents and straighten things out..

I would try this out but i would need a drop checker to now for sure if the co2 is in the desired level in the tank.

Thanks

 

[Sploke]

You can buy small bottles of oxygen at home depot used for brazing, one of those with a regulator might work. I don't see any reason why you couldn't adjust it well enough that you aren't just pumping O2 into the tank, but it would be pretty difficult. Not to mention the added cost and complexity of getting it all run. With the cost of sugar and yeast being so low, its probably not very practical, but would be interesting to see if its possible. But, if you're getting into keeping a bottle of O2 and a regulator around, might as well just go pressurized CO2 at that point and skip all the crap in the middle.

 

[Bk718]

You think the airpump even with the control valve will release 2 much o2??

Who knows maybe i will give it a shot, or perhaps someone with a drop checker who saw this thread may take a stab at it..

 

[Sploke]

I don't know, I'm just saying it would be a very fine line keeping the solution in equilibrium between putting it into the tank, or sending the yeast aerobic.

 

[PaulJ69]

Quick question. couldn't you just unscrew the cap, swirl the mixer around to aerate it and then cap it back off. Or will it eventually turn anaerobic and stop?

 

[Bk718]

Quick question. couldn't you just unscrew the cap, swirl the mixer around to aerate it and then cap it back off. Or will it eventually turn anaerobic and stop?

when you unscrew the cap you let out any of the co2 pressure you already had in there, so by the time the pressure builds up again who knows what stage the yeast will be in. And the yeast doesnt necessarily stop when it goes anaerobic, it just produces less co2 as opposed to aerobic.

 

[Carissa]

The only way I can picture this working is if you have your co2 output line at the lowest possible point in the bottle - right above the water line. Then even if oxygen does get into the air in the bottle (which it will - it will attempt to come to equilibrium with the water just like co2 does), it will rise up above where your output line is and hopefully you would only be sucking mainly co2 out of the bottle rather than oxygen. I thought about this too, but I decided that the chances of sucking up foam/liquid into the tank were higher than the benefits. Plus, it's easy to overcome slow production by just using another bottle inline or adding more yeast to the mix.