# DIY Co2 - two bottle system, frustrate out of my mind!



## Nlewis (Dec 1, 2015)

Rinfish said:


> All right guys, i'm at my wit's end, here.
> 
> I've had a DIY co2 , two bottle system set up for a few months now, and can not, for the life of me, manage to maintain a 2 BPS consistency. Any/all help is appreciated. Any formulas i should try, precautions, etc.
> 
> ...


IMO you will always struggle with consistency with diy co2.


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## Rinfish (Aug 16, 2015)

That's a bummer. =( I hoped with a two bottle system I might have enough consistency to keep co2 up to decent levels.

I've tried ways to increase the amount of dissolved co2 into the system. Initially I ran the co2 straight into my intake, but my eheim inevitably filled with bubbles which it would shoot out in bursts. Right now I have the diffuser underneath my output flow and it seems to catch maybe 40% of the bubbles, sending them around the tank. 

If anyone has any other methods that work please let me know!


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## Rainbow4000 (Jan 24, 2016)

Well, what I use is two large/deep plastic jar lids under the bubbles with the filter spray bar a few centimeters below the water level directed onto the CO2 collected in the lids. My drop checker can be quite light green most of the time. I leave the CO2 on all the time and its production usually lasts two weeks. I have two bottles so I can change one at a time.


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## Nordic (Nov 11, 2003)

I have learned not to fuss too much with the variation in the DIY CO2 output. That is when you get unwanted results, yeast spills, black hair algae, fast pH shifts and just about all the possible negative things CO2 could do.

If it happens slowly, I think the tank gets time to adjust to it.
I don't fuss if CO2 is slow to build up, especially if I let the previous bottle run its course.
I don't rush to make a new bottle the moment bubble count slows down a bit.
Try to feel the natural pace. When it is cool in the morning output is less than it will be later in the after noon.
Find the point where your bubble rate is more or less acceptable for most of the time, stick with it.
It is not pressurised CO2, you will NEVER be able to dial it in to the same precision without some kind of pressure regulator.

Don't feed or light more than you can provide CO2 for.


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## No.92 (May 1, 2016)

Dump the yeast method and switch to the citric acid and baking soda method. You'll get instant pressure right from the start and you will easily get over 2bps. It will be a stable pressure right until almost the end.


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## R|M|D Photography (Apr 9, 2016)

I agree, Citric Acid and Baking Soda is way more consistent and no smell.


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## burr740 (Feb 19, 2014)

You should be able to run 2 bps fairly consistent using a 2 bottle system, changing 1 bottle per week.


Couple things that stood out to me:

*"Drop checker in 2 liter soda bottle"*

I dont understand this, how is a drop checker inside a 2 liter bottle?

*mixed tepid/warm water with sugar + dechlorinator 3/4 the way up to the bottle*

Skip the dechlor, dont need it

*add 1/4 - 1/2 tsp active bread yeast (refrigerated) into shot glass with sugared water from bottle, mix until foamy*

Mix until foamy? Just need to gently stir the yeast in then let it sit for a few minutes until it begins to foam.

*add to bottle and shake*

No need to shake, just pour the yeast water on top and leave it be.

1/2 tsp is good for 2 liters of water and 2 cups of sugar. More yeast = more co2 but the mixture wont last as long. Day in day out consistency is the goal. Be sure to use the same amount of yeast each time. 

Should be able to get 1bps consistently out of each bottle for about 2 weeks. Change out 1 bottle per week, never both at the same time. It's a good idea to have a bubble counter so you can keep an eye on the system's output. As soon as you notice any reduction it's time to change out the oldest bottle. Ideally just prior to it slowing down. 

To get more longevity use less yeast. May have to play with the recipe a few times to get it right. Consistency is key. For example 1 bps for two weeks straight is better than 2 bps for a few days, then 1, then back up to 2, etc 


Ive never used a cut off valve with DIY, it's just one more thing to go wrong/leak/ depressurize the system, etc. DIY should be kept as simple, and stable as possible. Running 24/7 is fine.

Speaking of leaks, check every connection thoroughly with soapy water or toy bubble solution. When you are satisfied there are no leaks anywhere....check them all again, and again a few days later. The tiniest leak anywhere throws the whole system out of whack. 

Here is the DIY set ups Ive done in the past, may get some additional food for thought

http://www.plantedtank.net/forums/2...-others-build-thread-performance-reports.html


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## Bandit1200 (Dec 11, 2010)

I was using 3 bottles for yeast and had much better consistency. One factor for my setup that may have been an issue with controlling the consistency was my diffusion system. I was using a Red Sea Reactor 500 and was getting good diffusion/results with it. In my case as long as there was a minimum/steady output of CO2 the reactor would use it all and any spikes in the output were just blown out as bubbles instead of being diffused. After observing this I just made sure that I changed out a bottle frequently enough (generally one every weekend) that there was always slightly more output than the reactor was using and it was steady sailing from there. As long as it "burped" occasionally all was good.


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## Hoppy (Dec 24, 2005)

The system that link leads to is a citric acid system, not a yeast system. If you use it as it is illustrated, and use yeast, it won't work.


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## cjp999 (Nov 18, 2008)

I used 4 bottles on my 46g, rotating in 1 fresh bottle a week. I got pretty good consistency and drop checker was usually close to green. I got full diffusion with my reactor.

One thing to note is that your water chemistry can have big impact on how your yeast "burns" through the sugar. I'm on a well with fairly hard water. I tried RO and also softened water. One gave a very low but long lived production. The other produced a lot over a few days, and then not much. I eventually just tried the untreated well water and found it gave the most steady production and also the most total production over the 4 weeks. I added a couple of tablespoons of baking soda, even though the pH is already 8.4. This seems to extend the production cycle quite a bit.

Regarding activating the yeast, I found I needed to activate it with near scalding hot water. The instructions say "warm" water, but then say 100 to 110F. I consider this hot and found if it was not hot enough to make me pull my hand out from under the tap after a few seconds, then it usually didn't activate the yeast well. Make sure you are getting a good amount of foam after 10-15 minutes (like 3/4"). Otherwise it's not activated.

Also, the brand of yeast will also have an impact on the CO2 production. I used Fleischmanns. That's not to say it is best for all situations, but with my water and my 4 week approach, I felt it did really well. Getting a green (or at least nearly green) drop checker on a 46g with just one fresh bottle a week is pretty good by most counts.


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## Nordic (Nov 11, 2003)

Wine yeast is even better, you can drink the stuff from your CO2 bottle....


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## MCSLABS (Apr 19, 2016)

Give this a try and inject it right next to your filter out flow so it will drag the bubbles back into the tank


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## Beamer (May 5, 2016)

Rinfish, I think Nordic is right don't expect a Yeast system to be as controllable as a pressurised system, just settle down to a consistent mixture that is slow and steady. You could add an empty tank to the system as the extra volume will reduce the pressure variations caused by the varying rates of CO2 production. One thing is absolutely certain, DON'T put a valve in the system and shut it down over night. The rise in pressure in a small volume system is a real risk. Bottles can and do explode and you sure don't want that! The second reason is that the wildly fluctuating pressures day to night will make setting the restrictor valve a nightmare, but I think you found that already.


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## Powerclown (Aug 17, 2014)

Get yourself a cheap paintball co2 system,even the little 12oz. runs 2 month or longer with no problems.


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## GrampsGrunge (Jun 18, 2012)

The point is these systems work without needing a CO2 bottle, regulator and all the other stuff.

It's low tech simplicity, I used Yeast/Sugar on my tanks back in the 90's, and I was using less CO2 than these 2 and 3 bottle systems use, and still had what I considered good plant growth. Especially under a rather hot and bright phosphored Mercury vapor lamp on the 29 gallon.

Water that normally was 7.5~ pH and 4 dH out of tap would be @ 6.9 in the morning and would slowly go back to 7.0~7.1 before the lights went off. No need for timers and solenoids or cheap regulators that 'dump' when the bottle gets close to empty

CO2 as nature intended. :grin2:


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