# Diy Co2



## Darkknight512 (May 29, 2010)

I'm thinking of setting up a DIY CO2 system. How much yeast and sugar would I need for a 5 gallon tank? This will all be setup in a 2 liter bottle. Also is it possible for the bottle to explode? 

Thanks.


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## Darkblade48 (Jan 28, 2008)

The ratio is usually 2 cups of sugar, and anywhere from 1/4 to 1/2 a teaspoon of yeast, depending on the initial rate of CO2 you want.

It is possible for the bottle to explode, if the output is blocked, and sufficient pressure builds up.


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## Darkknight512 (May 29, 2010)

For my 5 gallon tank, is I want just a little CO2 so I can ramp it up later, how much yeast/sugar would I need an how long would each mix last?


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## Darkblade48 (Jan 28, 2008)

I would start off with a little bit of yeast, maybe as little as 1/8 of a teaspoon. 

I would expect the mixture to last about 2-3 weeks, at best.


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## Darkknight512 (May 29, 2010)

I'm thinking of instead of going CO2 going for some Flourish excel instead. However I heard that it can kill some species of plants (which I don't have any of) and some invertebrates. Will I have any problems dosing 0.5 ml per day in a 5 gallon tank with ghost shrimp and eventually something like cherry shrimp?


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## Darkblade48 (Jan 28, 2008)

You should be fine as long as you adhere to the recommended dosages of Excel.


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## waj8 (Jun 30, 2010)

I would go with the excel. The tiny amount of CO2 required is very difficult to produce in a steady manner using DIY CO2. The larger the tank the easier it gets. The details of how to make a kickass recipe are on my website but it probably won't work for a 5 gallon tank. I would say it's not worth the trouble..


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## camboy012406 (Jun 11, 2010)

never try diy co2 you will regret it. as i have experienced before all ky ghost shrimps died. currently on my 5.5gal im using just flourish excel once a week after 20prcent water chnge.


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## pat3612 (Jan 29, 2008)

Ive never had any deaths of shrimp with diy co2 but with a 5 gal you prob are better just using excel. My 10 gal shrimp tanks have diy co2 and the moss grows like crazy.


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## waj8 (Jun 30, 2010)

I use DIY CO2 on my 120 gallon planted Discus tank. No issues really. It takes two 6 liter bottles to do the job. The small tanks are much more difficult. You cannot say never try it. I have been doing this for many years. However, if you have fish in a small tank, I think you are taking a risk. Also, if you cannot get a steady flow of CO2 you will also likely have algae problems. DIY CO2 would be easier to achieve in a small tank without fish or shrimp in your tank as CO2 overdoses would not matter so much.


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## Darkblade48 (Jan 28, 2008)

Can you actually get 30 ppm of CO2 with only two 6L bottles of CO2 on a 120g aquarium?


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## waj8 (Jun 30, 2010)

No problem. For some reason there are quite a few false ideas about DIY CO2 floating around the internet. I guess no one takes it very seriously. However, it is simply not true that DIY CO2 is not good for large tanks, or that it only lasts 3 weeks at best, any yeast will do the job or production is too uneven to be useful. I have recorded the bubble count on my current setup. The recipe is at http://planted.mnsi.net/CO2 Generator.htm and the bubble count is at http://planted.mnsi.net/CO2 Production.htm


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## Darkblade48 (Jan 28, 2008)

For your bubble count graph, what do the different series (CO2 blue and CO2 green) mean? I assume they are two different jugs of DIY CO2?

What do the numbers on the ordinate axis represent? I assume the abscissa is days. I have a suspicion that the ordinate axis is a bubble count (per minute?)

How do you know you are achieving sufficient CO2 diffusion?

Why the addition of the copper? I doubt hydrogen sulfide will form that readily. Also, if copper is toxic to yeast and bacteria, why does it not kill the champagne yeast?


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## waj8 (Jun 30, 2010)

The graph is bubbles per second verses days. There are two bottles started 3 weeks apart. The upper line is the combined output of the two bottles. Each bottle is changed every 6 weeks and yeast is added to each bottle every 3 weeks. So every 3 weeks I have to change the mixture in one bottle and add yeast to the other bottle. Sorry about the poor presentation. I guess I will have to work on that.

I have no idea if the copper makes any difference or not. I have never tested the recipe without it. I have noted that the copper is very shiny when I change the bottles. It is something that I started doing years ago based on ideas from people that made their own wine. I also spoke at length with someone from Hiram Walker distilleries to come up with the recipe. I only mention it in the recipe just in case it actually does make a difference. The yeast does not seem have a problem with the copper at all.

I am not a beginner at this. I measure CO2 in the usual manner. I also use a form of dropchecker to double check my CO2 levels. Maybe once or twice a year I get a stuck fermentation, so I check the bubble count and CO2 levels fairly frequently. I find the tank CO2 levels do not fluctuate that much considering the CO2 production is somewhat erratic.

I am not saying that DIY is better than pressurized, just that it is a lot better than people think. I think it is particularly unsuited to small tanks. It's hard to reach the critical mass necessary to get a good fermentation going and it is more work than pressurized. Hardly seems worth it when excel is available. Due to the cost though, I would not want to use Excel on a large tank.


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## Darkblade48 (Jan 28, 2008)

If the ordinate is indeed bubbles per second, how can you count upwards of 40 bubbles per second?  

I am not sure what your "usual" method of measuring CO2 is, but unless it is using a drop checker with a 4 dkH reference solution (not aquarium water, not tap water, not distilled water), then I would not find it very reliable.


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## BettaBeats (Jan 14, 2010)

diy co2 is hard to maintain on small tanks. i had a 600ml bottle for my 10 gal that gassed out my shrimps at night.

im going to try again with a timer set up to turn on an air pump when the lights go off.


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## pat3612 (Jan 29, 2008)

Two comments remember not to fill the bottle more then 3/4 full. I think lots of people make the mistake and then it leaks into the tank. I use the 2 litre bottle on the ten gals.


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## waj8 (Jun 30, 2010)

Darkblade48 said:


> If the ordinate is indeed bubbles per second, how can you count upwards of 40 bubbles per second?
> 
> I am not sure what your "usual" method of measuring CO2 is, but unless it is using a drop checker with a 4 dkH reference solution (not aquarium water, not tap water, not distilled water), then I would not find it very reliable.


Yikes. Sorry it's bubbles per minute. I forgot that I did it that way. You know instead of criticizing me, why not give the recipe a try? Or come up with one that is better. I am not fibbing about that bubble count. Send me a PM and I will send you a package of yeast with a homemade bubble counter and a stopper to put on a two liter bottle as soon as I get back from vacation.

I have known how to measure CO2 in a planted tank for 15 years. I use A 4.5 kH solution and a bubble counter. I also check the the pH and kH with high quality test kits and use the CO2 chart. You cannot say that a dropchecker is particularly accurate either. There is no way the colour in a dropchecker accurately reflects the CO2 concentration any more than a cheap pH test kit accurately reflects the pH. It's a rough guide only. Unless you know the pH very precisely you cannot accurately measure the CO2 concentration.


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## coldmantis (Apr 5, 2010)

is there any way to tell if I need to make another batch of co2 by the colour of the mix in a clear 2l bottle? does it turn white or yellow or something when it's almost out?


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## Darkblade48 (Jan 28, 2008)

waj8 said:


> Yikes. Sorry it's bubbles per minute. I forgot that I did it that way. You know instead of criticizing me, why not give the recipe a try?


Not criticizing you in particular, I just wanted some clarification on some of your figures.



waj8 said:


> I have known how to measure CO2 in a planted tank for 15 years. I use A 4.5 kH solution and a bubble counter. I also check the the pH and kH with high quality test kits and use the CO2 chart.


As you know, trying to check the CO2 using the pH and kH method (i.e. by testing your aquarium water) is not the best way.



waj8 said:


> You cannot say that a dropchecker is particularly accurate either. There is no way the colour in a dropchecker accurately reflects the CO2 concentration any more than a cheap pH test kit accurately reflects the pH.


Correct on the pH test kit, but with a drop checker, the solution is made so that there are no other factors that may influence the kH test kit.



waj8 said:


> It's a rough guide only. Unless you know the pH very precisely you cannot accurately measure the CO2 concentration.


You also need to know the kH of the solution (knowing that there are no other influencing factors).

People have designed drop checkers that used pH meters before. They work, but are somewhat clumsy to use.



coldmantis said:


> is there any way to tell if I need to make another batch of co2 by the colour of the mix in a clear 2l bottle? does it turn white or yellow or something when it's almost out?


Not really; just keep an eye on the bubble production.


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## waj8 (Jun 30, 2010)

You really need a bubble counter. I would say even more so with DIY. Fermentations will sometimes become stuck. Sometimes just giving the bottle a shake will fix it, sometimes you have to add a bit more yeast. With most recipes the fermentation typically becomes stuck long before even half the sugar is used up.

Anthony, I find that trying to determine pH using bromothol blue is pretty inaccurate. While the KH in a dropchecker is controlled very precisely you are still stuck with trying to look into your tank and compare shades of green in a range where the difference between colors is very subtle. Errors in pH measurement skew the CO2 concentration results worse than small errors in kH measurement too. I feel that people usually overstate the precision of their CO2 measurements. I also think it doesn't matter that much. Dropcheckers are the most clever and useful things. I love them. I often wonder who invented them.


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## BettaBeats (Jan 14, 2010)

Bubble counters and drop checkers aside..

you also have to understand that DIY diffusion methods arent the most accurate either. I learned a big lesson when I pumped the CO2 into my AquaClear 30 intake as opposed to my Whisper 10 - the diffusion of the CO2 into the water was far greater in my AQ30 and thus I was unknowingly gassing my tank occupants at night  

What I do for a 1L bottle is a cup and a quarter of sugar, and a 1/4 tbsp of yeast. 3/4 of the bottle I fill with WARM *not* HOT water, add my sugar, then my yeast.

Problem with DIY Co2 is, that with only one bottle of CO2 the bottle might go for 3 days with vigorous co2 pressure and that will be too much co2, before it slows down to a steady 1-2 bubbles per second for the next 2-4 weeks, then it might go another two weeks at a slower rate than 1 bps.

With two bottles you can let the new mixture gas off the intense co2 production then wait for the right flow and switch off the expired mixture with the new one.

That being said, I have also done experiments on what is the best mixture for my use. Some of the formulas online are for larger tanks and therefore more CO2 production which can be deadly on a small tank (like my 10g).

Sugar is cheap, so I'd maintain the cup to one and a quarter cup of sugar and fiddle with the yeast. maybe 1/8th of a TBSP to start. When CO2 production slows, add another 1/8th of a TBSP. You'll know when the alcohol caused by the fermentation has killed the yeast (as it should) because you will get NO CO2. It might even gas for a bit then suddenly stop if you add yeast in a second or third time.

DIY CO2 should be monitored.
One of my newest creations is a rig of a timer and an air pump with an air stone in my tank that will go on when the lights go off to oxygenate the water at night and to drive off the CO2 that isn't being used because photosynthesis has stopped.

My question with this method is how wild will the pH swings be in the tank?


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## Darkblade48 (Jan 28, 2008)

waj8 said:


> Dropcheckers are the most clever and useful things. I love them. I often wonder who invented them.


I am not too sure who invented the drop checker itself, but I believe the first "pioneer" to use a 4 dkH reference solution inside it was Hoppy, over at TPT, along with Tom Barr.



BettaBeats said:


> My question with this method is how wild will the pH swings be in the tank?


CO2 will drop the pH of the water only to a certain point; however, before this point is reached, it is more likely that your inhabitants will be gassed.

However, for just the pH swings, fish and shrimp should be fine. I have kept shrimp with my drop checker edging on yellow, and by morning it is blue again, so it is quite a big pH shift.


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## waj8 (Jun 30, 2010)

BettaBeats said:


> Bubble counters and drop checkers aside..
> 
> DIY CO2 should be monitored.
> One of my newest creations is a rig of a timer and an air pump with an air stone in my tank that will go on when the lights go off to oxygenate the water at night and to drive off the CO2 that isn't being used because photosynthesis has stopped.
> ...


I am not too crazy about that air stone method. I think the constant pH swings may be harmful to fish. Ideally you should have a way of limiting CO2 diffusion. A diffuser that works well at low CO2 production but has a limited capacity. Most diffusers are like this to some degree but for a small tank you need a very low capacity diffuser. Constant light surface agitation will also limit CO2 absorption. One of the problems with ACs is the surface agitation changes when the water levels change.

Another way to gas fish is to have a close fitting cover. The atmosphere above the water surface can become too rich in CO2. When that happens there is no way for the CO2 dissolved in your tank to leave solution and CO2 concentrations just build and are not limited by your diffuser capacity. I always used to have mystery fish deaths until I began making sure to leave 10% of the tank uncovered.

I would experiment with an air stone on a needle valve that is on all the time. That way you have some control over CO2 and don't get the sudden pH shifts. It will prevent too rich a CO2 atmosphere and also provide oxygen to your fish should something disrupt plant growth as well as provide oxygen at night. Depending on how much air you bubble through the air stone you may be able to limit the net CO2 absorption regardless of your CO2 production. Not completely, but at least to some degree.


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## BettaBeats (Jan 14, 2010)

waj8 said:


> I am not too crazy about that air stone method. I think the constant pH swings may be harmful to fish. Ideally you should have a way of limiting CO2 diffusion. A diffuser that works well at low CO2 production but has a limited capacity. Most diffusers are like this to some degree but for a small tank you need a very low capacity diffuser. Constant light surface agitation will also limit CO2 absorption. One of the problems with ACs is the surface agitation changes when the water levels change.
> 
> Another way to gas fish is to have a close fitting cover. The atmosphere above the water surface can become too rich in CO2. When that happens there is no way for the CO2 dissolved in your tank to leave solution and CO2 concentrations just build and are not limited by your diffuser capacity. I always used to have mystery fish deaths until I began making sure to leave 10% of the tank uncovered.
> 
> I would experiment with an air stone on a needle valve that is on all the time. That way you have some control over CO2 and don't get the sudden pH shifts. It will prevent too rich a CO2 atmosphere and also provide oxygen to your fish should something disrupt plant growth as well as provide oxygen at night. Depending on how much air you bubble through the air stone you may be able to limit the net CO2 absorption regardless of your CO2 production. Not completely, but at least to some degree.


I have drawn a line on the tank for my 'optimal' water level. I am still scared to try CO2.. I have slow growing plants that do pearl near the later parts of the day. Might just leave it like this for a while.


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