# DIY CO2. Can you use a valve to control amount?



## wood (Nov 15, 2006)

I am using a 2 liter DIY CO2 with a hagen ladder to dissolve the bubbles. I have to use an bubbler under the ladder periodically throughout the day in order to keep the ph from dropping too low. My ph will drop below 6 if I allow all of the CO2 to dissolve. The bubbles interfere with the CO2 and make the CO2 run up the ladder extremely fast causing pretty much none to dissolve. I have been testing my ph in order to find the right timing of the bubbler to keep the ph constant around 6.5. It is a major pain in the arse.

Instead of wasting so much CO2 can I use an in-line valve in the CO2 line to lessen the bubble rate of the CO2, thus saving CO2 for the long run? I am using poly tubing and can get an in-line valve to control the CO2 bubble rate going into the ladder. Of course the biggest concern is will I cause so much pressure to build up in the bottle that it will explode? 

I could also t-branch the tubing to another empty 2-liter bottle to allow the extra CO2 to build up in another container to lessen the pressure in the "fermenting" container basically giving the CO2 twice the volume to build. It would be a ghetto pressurized CO2 system but since my 10 gallon doesn't need much co2 I would rather save the CO2 than waste it and have to make a new batch every week.... Perhaps you could also increase the size of the operation and make DIY CO2 last even longer? 

Let me know what you guys think.

Ryan

The Valve

The T-Branch


----------



## yoink (Apr 21, 2005)

I think the bottle will explode from the pressure build up. Is there any reason you don't want the ph lower than 6.5?


----------



## wood (Nov 15, 2006)

yoink said:


> I think the bottle will explode from the pressure build up. Is there any reason you don't want the ph lower than 6.5?


I have Cherry Shrimp and Otto's and both don't like low PH.

You don't think that the extra container will alleviate the pressure problem?

Does anyone know at what pressure a 2 liter will explode? I will try to find that out. Google........


----------



## TAF CAF (Jan 12, 2006)

I would be very concerned in the pressure you would build up in your bottles (even connecting two).

Perhaps a better way would be to use a two outlet control valve and just bleed off the tiny bit you don't need... that way you could adjust the bubble rate without causing pressure build up.

Alternativly, I would recomend downsizing your reactor if you are coming up with much too much CO2. Cut your mix in half, and possibly reduce the yeast to about 1/4. Also, adding a teaspoon of baking soda will slow down your reaction... producing a slower but longer rate of CO2.

Of course, you will probably want to play around with it while leaving your current system as is, since big fluctuations in CO2 favors the outbreak of algae.


----------



## fish_lover0591 (Nov 11, 2006)

this sounds interesting. are there any other things you can use to contain the yeast and etc in that can handle high pressures besides 2 liter bottles ? An extra container sounds cool but won't help your issue. Wait how about putting the 2 liter bottle in a bucket with an aquarium heater and adjusting the temps to get the bubble rate you want ? higher temps = more co2 
lower temps = less co2  But you need to find out what temps yeast will die at and be fine at. ex: lowest temps, highest temps they will survive at .


----------



## Wasserpest (Jun 12, 2003)

Don't... is all I can say. Yeast fermentation can create extreme pressure, definitely enough to shatter glass bottles.

You can use a valve to control DIY CO2 if you use it at one end of a T, so when the valve opens the CO2 will just escape into the atmosphere, when it closes it goes into your diffuser.

While this would work, you are looking into spending money that you could use towards a much more convenient pressurized setup.

Better to reduce the bottle volume, that would be the simplest way of adjusting the amount of CO2.


----------



## yoink (Apr 21, 2005)

I wouldn't mess with it unless you see problems from too much co2. I've kept cherries and otos in a ph of 6.5 and wouldn't worry about taking it lower if need be.


----------



## wood (Nov 15, 2006)

I really don't think that after adding another bottle there could be a serious risk of having one of the bottles burst. After about a week the bubble rate is just about where I want it to be, which means for the first week I would be "storing" about 1/2 of the overall generated CO2 in another container. Basically for the first week the bubbles are coming out twice as fast as I would like. Twice as fast means a lot more undissolved CO2. The faster they move up the ladder the less gets dissolved. Using a valve would make it a controlled release and thus having the bubbles emit at the exact rate you want according to the ph you want.

Ya see the problem is not the time it takes for the yeast to die off, but instead the amount of wasted CO2. The yeast could die off long before I run out of CO2 if I could figure out how to safely do this. Achieving the least amount of wasted CO2 would really help especially in the long run. Perhaps instead of using (2) 2-Liter coke bottles, why not something stronger? The reason why the bottles burst is because of the plastic. The plastic can't hold up to high pressure. The reason why CO2 canisters are metal. 

I am going to do more research into this. If I could find a better airtight container that could withstand higher psi then I could make a huge batch of yeast/sugar that could last a while using a valve....... Poor man's DIY pressurized CO2. Maybe a thermos container?? Give some ideas..

Some would say why waste the time, just go pressurized. But I figure the amount of money you could save versus buying a whole pressurized system and having to refill. When all it would take is some cheap poly tubing, cheap valves, cheap containers, yeast, and sugar. 

In the end it is all about avoiding an explosion. Hehe. 

Lemme know what you think.


----------



## fish_lover0591 (Nov 11, 2006)

hmm i'm not sure what you could use...i will tell you if i think of anything  and the method of using a bucket with water and a heater does work since i seen someone do it on this site


----------



## blueguppygirl (Oct 30, 2006)

This is just my P.O.V. but in my 10g I use a 2l bottle/20oz DIY. I've been tinkering with a recipe that so far has lasted a couple weeks and I haven't had too much co2. It takes a little longer to make but for me it's worth it. I can send you my recipe if you like but I'm not finished tinkering yet.


----------



## rishy21 (Aug 20, 2006)

If you cool the yeast-sugar mix bottle with some ice on the outside.. it will decrease the rate of fermentation and thus CO2 produced.
I haven't tried this but just a thought that struck me .. maybe this is one way of taking care of CO2 production rate .. 
Opinions please folks.


----------



## D.gilly (Sep 25, 2005)

i have an old school valve that basically leaks the pressure its kind of like a needle valve that has a hole in it as you decrease air flow ( its ment for o2 pumps ) it leaks the air that normally would be just going through if you look around you may bee able to find one. mine is lime green.


----------



## Rex Grigg (Dec 10, 2002)

How about moving the bubble release point closer to the top of the ladder? Am I the only one that noticed this obvious method?

Trying to control the output of a yeast based system with any type of non-relieving valve system is asking for trouble.


----------



## yoink (Apr 21, 2005)

You could run it into the venturi line on a pump and have the pump turn off at night also.


----------



## wood (Nov 15, 2006)

The issue is simple, yet complicated. With DIY CO2 there is a ton of wasted CO2 since the output of CO2 is high in the beginning and gradually decreases. This not only causes you to have to make a new batch every week, but also causes inconsistent CO2 levels. Using DIY CO2 places you completely dependent upon the fermentation process, meaning the CO2 output is directly related to the fermentation without anything other means of controlling the CO2. Pressurized is better because you can control it, obviously.

That is the simple part, simply knowing that the yeast has complete control over you. :icon_cool 

The hard part, which I am going to attempt to do, is trying to control the output by "storing" the excess CO2 in order to achieve a more consistent and long term CO2 output. Incorporating a device to also completely shutoff the CO2 output at night is obviously an even riskier proposition.

I am not an expert at physics, but I think with some research, and experimenting, I could devise a method to "store" the excess CO2 and control the output. PSI is the main issue. CO2 pressure differs when temperature is increased or decreased, hence why cooling can make it come out slower and last longer. If I could find a CO2 reservoir that can handle a lot of PSI than I could make a big batch of CO2 without worrying about explosion.

First I need to figure out the total volume of CO2 that is outputted given the mix of yeast/sugar that I use.


----------



## yoink (Apr 21, 2005)

Have you tried using two bottles and staggering the refills between the two? I think that and tinkering with the recipe would give you a more consistent co2 content.


----------



## wood (Nov 15, 2006)

yoink said:


> Have you tried using two bottles and staggering the refills between the two? I think that and tinkering with the recipe would give you a more consistent co2 content.


I haven't tried anything as of yet. I think I am going to start with 3 x 2L bottles. One of them being the fermenter (red) and the other two being reservoirs. I will have valves for each bottle (olive) as well as the main valve leading to the tank. I will t-branch both reservoir bottles (green) and use an elbow joint (green) for the fermenter bottle.


----------



## BlueRam (Sep 21, 2004)

wood said:


> Ya see the problem is not the time it takes for the yeast to die off, but instead the amount of wasted CO2. The yeast could die off long before I run out of CO2 if I could figure out how to safely do this. Achieving the least amount of wasted CO2 would really help especially in the long run. Perhaps instead of using (2) 2-Liter coke bottles, why not something stronger? The reason why the bottles burst is because of the plastic. The plastic can't hold up to high pressure. The reason why CO2 canisters are metal.


Hey there Sparky, looks like you have a few ideas mixed up. First of all CO2 canisters are seamless metal because at room temperature CO2 remains a liquid above ~800 psi. Yeast survival is limited in both the % alcohol and CO2 pressure. 

Next, DIY is cheap (~$5 to start!) but requires a lot of work. Compressed is expensive (>$150?) but goes for months (or years). The old time or money balance.

The 3 x 2L bottle idea will work as follows: The gas generated in container A with increase the pressure evenly in A, B, and C and eventually generate bubbles in the aquarium. At that point the pressure in the reservoir is stable and each unit of gas produced in A goes directly into the aquarium. No appreciable volume of gas is "stored" (ok, about 4L at 2-10 psi) with the major effect of increasing (>3X) the time for bubbles to start.

So as posted elsewhere, rotate 2 or more bottles for consistency and lean out the yeast/add backing soda to increase the duration of a charge.


----------



## retoid (Jan 2, 2007)

anyone know how much pressure diy co2 creates?
in psi?


----------



## BlueRam (Sep 21, 2004)

retoid said:


> anyone know how much pressure diy co2 creates?
> in psi?


Given that a working DIY displaces water, and that 1-foot-high column of water exerts 0.44 pounds per square inch (psi) (Howstuffworks "Why can boats made of steel float on water when a bar of steel sinks?") I would refine my guess to <1 psi.

Now who would know much pressure a soda bottle can hold? 

"In order to find the failure point of the bottles they hooked up the pneumatic pump from Grant's "Deadblow" battle robot. The soda bottles exploded at 150 psi and the water cooler bottles exploded at 95 psi, so they decided that using soda bottles was better for the test even though they got much more lift out of the water cooler bottle."

Annotated Mythbusters: Episode 42: Steel Toe Amputation, Bottle Rocket Blast Off

Edit: "Documentation" of yeast explosion in glass bottle: Exploding Yeast Bottles!


----------



## retoid (Jan 2, 2007)

haha cool! and thanks


----------



## tusk (Jan 30, 2006)

I would move the output on the ladder first, cough up the $$$ for a real CO2 second, but....... at your own risk..........

I ran a 2L DIY CO2 with a valve for a while. I then found a different container that was better for many reasons (Basically an insulated 2L thermos. If you've ever used a cryo-cuff, you know what it is). I ran that with a valve. It worked fine...... for my settings...... at my own risk.


----------



## TAF CAF (Jan 12, 2006)

wood said:


>


Maybe I am just not understanding the idea here, but how are you going to get the CO2 out of the 'storage' bottles once the pressure is decreased? And where is the air going from the bottles while they fill with CO2?

As far as it looks like, you will pump the same amount of air into your tank as you are doing now, but with the CO2 ammount greatly diluted by the common air in the 'storage' bottles.


----------



## fish_lover0591 (Nov 11, 2006)

ok i think basically wood wants to produce co2 in bottle #1 then have the co2 equalize their pressure in bottle #2 and #3 and use a needle valve to control the co2 from bottle #3 like a pressurized co2 setup. but he doesn't know how much pressure will be built up. I think wood should setup a blow off valve in bottle #3 just to be safe.


----------



## BlueRam (Sep 21, 2004)

fish_lover0591 said:


> ok i think basically wood wants to produce co2 in bottle #1 then have the co2 equalize their pressure in bottle #2 and #3 and use a needle valve to control the co2 from bottle #3 like a pressurized co2 setup. but he doesn't know how much pressure will be built up. I think wood should setup a blow off valve in bottle #3 just to be safe.


Ok, this makes little more sense with this function of the needle valve after 3. After further searching, it appears that Champagne approached 100 PSI during fermentation (aggressive yeast in a sealed container) with is then reduced after disgorging to minimize exploding bottles outside the winery. 

Champagne and Sparkling WIne: What it is and How It's Made

Definitely a candidate for "don't try this at home!"

To add something slightly useful: The blow off valve could added by making the 90* on #1 a T link like 2&3 with a quick fail plug.


----------



## Rex Grigg (Dec 10, 2002)

TAF CAF said:


> Maybe I am just not understanding the idea here, but how are you going to get the CO2 out of the 'storage' bottles once the pressure is decreased? And where is the air going from the bottles while they fill with CO2?
> 
> As far as it looks like, you will pump the same amount of air into your tank as you are doing now, but with the CO2 ammount greatly diluted by the common air in the 'storage' bottles.



This is correct. Unless you can "pump" the CO2 into the storage bottles under pressure all you are going to end up with is bottles full of CO2 at the same pressure. And until you fill the volume of the bottles with CO2 you will mainly be pumping air into the aquarium.


----------



## vidiots (Jun 17, 2006)

This thread really got me thinking, however I can't think of any sort of cheap simple DIY setup that would safely do this.

I was thinking that the only safe way to restrict the flow and cause a back pressure would be to have a pressure relief valve in line to vent the excess pressure buildup somewhere below the danger point. You would also need some sort of low pressure regulator in line after the relief valve and before the needle valve to maintain a constant pressure since your source is inconsistant. Without the regulator your flow of CO2 will still vary some based on the varying pressure behind the needle valve. With the relief valve you would still have excess CO2 going to waste. Unless you used a bottle with a much higher burst pressure rating than the yeast is capable of generating and a relief valve with a much higher rating or none at all since the pressure will always stay below the bottle's & plumbing's burst pressure. I'm sure that at some point brewers have determined the maximum pressure fermentation can generate and selected appropriate sealed containers.

I think that the expense of this, while still maintaining a DIY CO2 source instead of a pressurized system would just get you the worst of both worlds, expense and high maintenance.

If you want to have a more consistant amout of CO2 getting into the tank, you might wanna just try using smaller bottles and more of them swaped out at different times to maintain an average combined output.


----------



## vidiots (Jun 17, 2006)

BlueRam said:


> Given that a working DIY displaces water, and that 1-foot-high column of water exerts 0.44 pounds per square inch (psi) (Howstuffworks "Why can boats made of steel float on water when a bar of steel sinks?") I would refine my guess to <1 psi.


This assumes that there is no restriction to the flow. A restriction to the flow will cause the pressure to be higher behind the restriction. If the water in the tank is the only flow restriction the pressure in the line will balance out with the weight of the water above the output which would work out to about 0.036psi per inch of depth. This also asumes that the tubing itself is large enough so that it doesn't count as a restriction because then the pressure in the bottle would be higher than the pressure in the tubing.

As for how stuff floats, your guess is close but it's more than weight per area, it's weight per volume or density. Boats are hollow meaning low weight per volume because most of the space is filled with much lighter air, they sink when they fill up with heavier water. Pure water has a density of about 0.998 grams per cubic centimeter at room temperature and a density of about 0.99997 near freezing. Anything less dense than water will float, anything more dense than water will sink. Salt water is more dense than Freshwater because it has more disolved heavy materials so it's density may get as high as 1.03 grams per cubic centimeter. Air has a density of about 0.0012 grams per cubic centimeter.


----------



## wood (Nov 15, 2006)

OK. The three bottle theory is no good. It is true that the pressure will reach a point where there will just be CO2 sitting in the three bottle without enough pressure to release into the tank. 

Here is another option.... What if I were to use another container? A container which could withstand a lot more pressure than a 2L bottle? Suppose there was a container which would withstand the entire output of CO2 without release? Does such a container exist that could of course be used with DIY?

Is it futile to even think that the pressure could be controlled with such a container given the fact that maybe the valve or tubing connection could break due to the high pressure?

I am sure that there has to be a way to have DIY CO2 and be able to control output.

I think that this would be a good subject to invest in.... Let's get the minds together..

-Ryan


----------



## Rex Grigg (Dec 10, 2002)

Since DIY can't generate a lot of pressure your idea is pretty much doomed to fail. You would need a very large cubic volume to hold the CO2 under what little pressure you can generate with DIY CO2.


----------



## essabee (Oct 7, 2006)

I believe we can do more with DIY CO2. We can control input, timer and flow. This was what I was trying when I wrote http://www.plantedtank.net/forums/diy/39157-diy-co2-reservoir.html


----------



## TheAquaNoob (Feb 8, 2006)

For those still interested in entertaining this idea, has anyone thought of using baloons for storage instead of bottles??


----------



## Rion (Dec 29, 2006)

Instead of controlling the amount of CO2 physically why not control it chemically? lessen your yeast in the mixture and you will produce CO2 at a lower rate and your mixture will be extended in it's life. The only problem is as with all DIY CO2 there is no precision in it at all just a limitation in the amount of CO2 created at one time. The exact amounts to use I have no idea because there are too many factors to take into account so there will have to be some experimentation with different amount of yeast. But the nice thing about controlling it chemically it won't cost you anything since you already have it all, in fact you'd be cutting costs in your demand for yeast.


----------



## vidiots (Jun 17, 2006)

Rion said:


> Instead of controlling the amount of CO2 physically why not control it chemically? lessen your yeast in the mixture and you will produce CO2 at a lower rate and your mixture will be extended in it's life. The only problem is as with all DIY CO2 there is no precision in it at all just a limitation in the amount of CO2 created at one time. The exact amounts to use I have no idea because there are too many factors to take into account so there will have to be some experimentation with different amount of yeast. But the nice thing about controlling it chemically it won't cost you anything since you already have it all, in fact you'd be cutting costs in your demand for yeast.


That is exactly why I recommended using multiple smaller bottles who's starting times were staggered to produce a more constant average total CO2 output.


----------



## epicfish (Sep 11, 2006)

I think the staggered bottle is a great idea for constant CO2 production. Another thing could be to keep the bottles in a tub of water heated by a regular aquarium heater. The heater could be put on a timer to shut off at night and then turn back on during the day. This would keep the temperature somewhat constant throughout the day, even in the early morning and later at night when the ambient temperature drops.


----------



## fish_lover0591 (Nov 11, 2006)

Lol Epicfish thats what i said earlier.


fish_lover0591 said:


> Wait how about putting the 2 liter bottle in a bucket with an aquarium heater and adjusting the temps to get the bubble rate you want ? higher temps = more co2
> lower temps = less co2 But you need to find out what temps yeast will die at and be fine at. ex: lowest temps, highest temps they will survive at .


----------



## epicfish (Sep 11, 2006)

Er, oops. Didn't read the whole thread. =)


----------



## fish_lover0591 (Nov 11, 2006)

Its fine


----------



## SecretSquirrel (Oct 27, 2009)

Hmmm. This may sound strange and dumb, but with some ingenuity I bet the right person (probably not me) could make this work. I haven't read every page of this thread, but I doubt anyone has suggested a balloon bladder. My brother is a pro balloon twister and I have seen some incredibly strong and voluminous balloons. Instead of trying to store your surplus CO2 in a rigid container, secure a balloon (not quite sure of the best way, but I bet dental floss wrapped tightly would suffice).

You would probably be in uncharted waters here, but you might come up with a very practical solution you could share with the rest of us. I'm thinking a large enough capacity balloon should be able to handle the excess CO2 during the high output period and could then be used later. The advantage would be your fear of an explosion (at least a dangerous one) would be relieved if it fails--although your cat may never forgive you. The hard and theoretical part would be preventing the CO2 in the balloon from immediate delivery to the aquarium. A check valve would halfway accomplish this, but not allow return when you wanted it to later. I suppose that takes us back to square one now that I think about it. I'm sure there's an inexpensive solution to your problem. Now you've got me interested and I'm going to research this some more. Get back to you if I come up with anything useful.


----------



## nissky (Jan 10, 2008)

Doesnt seem practical at all, as has been mentioned.
If you want to store co2 it will need to be in a pressurised container.
This is DIY CO2, so much easier to just control the generation of co2 in the first place. That is, by adjusting the mixture...


----------



## Wasserpest (Jun 12, 2003)

I think the main problem with balloons is that you can blow them up with the pressure that DIY CO2 provides, but once they are full, then what? If you inject CO2 using anything that needs pressure (like a checkvalve, needle valve, airstone, external inline reactor, etc) it would be hard to get the balloon emptied.

Essabee has figured out a pretty interesting DIY CO2 storage solution. It's great if you have plenty space, time, even temperatures, sugar and yeast, and no means of acquiring a pressurized setup.

To go back to the OT though, it is pretty simple to turn off CO2 at night by turning off the powerhead that diffuses CO2, or adding a valve on a T that opens during night hours. Most folks using DIY CO2 run it 24 hours.


----------



## TAF CAF (Jan 12, 2006)

Also a great way to reduce the CO2 at night is to add a timed bubbler that will come on at night. It 'out-gasses' the CO2, and has the added benifit of agitation that will bring in more oxygen for the fish.

This would probably be my best suggestion when it comes to high output DIY setups. However, I don't particularly like walking the line of dangerous, so I just get my DIY producing moderatly and run a powerhead that slightly moves the surface. This seems to keep everything in check and is plenty for my medium light setup.

However, if you really wanted to get technical, you could probably set up a control with a preasure release valve. That way if the pressure got too much during the storage period, it would automatically release. The question would be... what PSI would the release have to happen at?


----------

