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Discussion Starter · #1 ·
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
 

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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?
 

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Discussion Starter · #3 ·
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........
 

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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.
 

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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 .
 

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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.
 

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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.
 

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Discussion Starter · #8 ·
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.
 

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

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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.
 

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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.
 

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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.
 

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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.
 

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Discussion Starter · #15 ·
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.
 

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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.
 

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Discussion Starter · #17 ·
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.

 

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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. :)
 

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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!
 
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