Making A DIY C02 Unit and C02 Mixture Article

ishar

MFT Staff
Jul 27, 2007
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sorry epond- I am unsure how to answer your questions :(.

khisanthax- well I don't think you could double up... 4 cups, to my knowledge, won't dissolve into what would be close to 1L of water. If you double the sugar than the yeast will likely die out before the sugar is used up, and if you double the yeast you will get more bubbles but for a shorter life span.

Having said that, I think if you used a bigger container you could double everything... but I don't think it would extend the life, only the CO2 production.
 

alter40

Superstar Fish
Nov 26, 2007
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Charlotte, NC
The other option that you have is to run two bottles if you really want to double it up you can attach two bottles to a T and run that to the tank but I don't know if that would be too much CO2 or not.
 

epond83

Large Fish
Mar 11, 2007
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I think if you doubled everything but the yeast it would last longer. If I remember right the yeast multiply until they run out of oxygen, then the stop reproducing and create CO2 among other things.

The yeast slows production of CO2 when the alcohol percent reaches deadly levels, and they start to die off, so if you have the same amount of yeast but twice the amount of solution they should be able to live longer.

Now that I think about this I’m thinking about changing my one bottle system over to a two bottle system but with half the yeast in each, and have a tee connecting the two before the tank. And in effect make them last twice as long, if not close to it.
 

Feb 19, 2008
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I have a three liter bottle so I wanted to maximize the space I have and not clutter around the tank. so using twice as much of everything would have been nice ... will too much co2 hurt the plants? or fish if I add them later?
 

Lotus

Ultimate Fish
Moderator
Aug 26, 2003
15,115
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Southern California
home.earthlink.net
Yes, if you have a tank larger than about 30 gallons, two bottles would be better. Some people use the gallon juice containers with success.

I would recommend that you stick to the quantities, more or less. They optimize the food/yeast ratios fairly well. Too much yeast uses up the sugar more quickly, but produces more CO2 in a shorter time. Too much sugar and not enough yeast will produce only a little CO2, but for a longer time.

You certainly don't want more volume than about 2/3 full for a bottle, or you risk having a problem with getting yeast into the tank.
 

ravichr

Medium Fish
Apr 18, 2005
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Mansfield, CT
I have a 14g with 5 fishes (listed below). I have a bunch of plants in the tank. Has anyone experienced issues with the fish by using the DIY CO2. In a small tank as a 14g, will the continuous supply of CO2 deprive the fish of Oxygen. (I never did well in Chemistry). Please let me know.
 

I just got mine going recently... I am waiting for one of those nano-diffusers I bought on ebay to hopefully spread the bubbles out a bit. Now, it jsut comes out as one big bubble and floats to the top where it bursts. I am not sure if this is even doing anything for the tank.

PS... I make beer also, so I know a little about yeast. The yeast actually never dies, it hibernates once it runs out of food. There are breweries in Belgium which are still using yeasts that are hundreds of years old. Theoretically, you could keep reusing your yeast, but it probably is not practical in a DIY set-up where the new yeast cost next to nothing anyway.
 

May 30, 2008
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Midland, MI
Love this thread, this section, this site!!! This site and all involved have made my fish-keeping experience more pleasureful than I ever thought and super intriguing. I have read all post on this thread and found that DIY CO2 doesn't look that hard to do. I set up two 2L bottles for my 29g, I also have a 5g...erm....bottle for my 55g. Not really a bottle @ 5g but hopefully I can produce enough CO2 with that, vs using 4-6 2L to get a desirable amount of CO2. I just finished putting everything together, ran the tube into the filter, have a check valve between tank and T that connects the two bottles. Simple set-up, cheap start-up/keep-up, gotta love the DIY!!!!!
 

epond83

Large Fish
Mar 11, 2007
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Yeah, the goal is to have the spline wheel that sucks the water up, chop up the CO2 bubble so there is more surface area and it can dissolve faster into the water.
 

PerenGee

Large Fish
Sep 20, 2008
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San Diego
This is sort of stupid but like Bl33dy, I too have a hanging filter, but I'm still confused as to where the tubing should go. Do I stick it directly into the top of the filter or submerge it next to the intake grating?

It would actually be really helpful if someone could draw it out, but that might be too much to ask. Oh also I should add that I haven't actually done anything yet, I'm just curious as to what the full process was, so no urgency.