Questions about DIY CO2.

NJ Devils Fan

#1 Devils fan
Oct 28, 2002
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Someone posted this on Orbitorly's website about DIY CO2. I e-mailed the person with some questions, but she hasn't got back to me and probably won't for awhile, so I figure people here could help.

"This contraption will put C02 into your freshwater or saltwater tank for your plants.

You will need-

:Yeast
:Measuring Spoons
:Warm Water
:Small Soda bottle With Cap
:Bubble Rock
:Plastic Tubing
:Super Glue

Wash out the soda bottle well. Fill with warm water about half way into the bottle. Add 1/2 teaspoon of yeast, and 2 tablespoons sugar. Shake and let sit.

Now take the washed cap and measure width of the tubing onto the bottle and make a hole for the tubing to securly fit into. NO air must leak through, and super glue will help with this if you put it all the way around the tubing where it meets the bottle. Put the stone on the end. Put the end in the tank, and put the cap back on the bottle.

There will be foam, thats okay. If its get to the top of the bottom, flick the sides of the bottle.

You just saved up to $300. Good Job. E-mail me with questions."


My questions are, If I use a 2 liter bottle instead of a 1 liter bottle, would I just double everything? When do I know that it is used up and I have to put more stuff in? When I put the tnd of the tube into the bottle, to I put it in the water or above in the empty part? Where shouldI put the other end of the tube with the air stone, like in the middle, infront or behind my driftwood, on he sides?
 
First off, I would use something like a juice bottle which tends to be a little more rigid than the 2L soda bottles. I used the fomula from:
http://www.thekrib.com/Plants/CO2/

I don't know for sure, but I would think you would really only need to double the sugar and water...you're depending on the yeast to reproduce, so the starting amount won't matter _that_ much.

You'll have a much better fit where the tube passes through the cap if you drill the hole with a properly sized bit. I sealed mine with silicone rather than trying super glue...super glue tends to be brittle and might crack over time from all the screwing on and off of the cap.

You know it's used up when your CO2 product stops. You'll be able to guage it well after the first few batches.

Placement of the outlet tube isn't really all that important if you're using an airstone. I don't use and airstone and just feed the output tube into my filter intake and let the impeller break up the bubbles. I've read that airstones will cloq quickly with CO2 and if yours were to clog completely, you'd have quite a mess when your bottle let loose. Basically, you want to maximize the CO2 bubble's surface area contact with the water to allow for maximum diffusion. Read on the Krib about bell diffusers...they work relatively well for a DIY setup and are definitely affordable.
 
Thanks for the help. When you said to use a juice bottle, I saw on the site that people said not to use bottles because they blew up and glass went everywhere. Is there something I have to vent or do I just leave the tube in the tank until it is finished?
 
Personally I use a 2 litre bottle, but glass would be fine too. If you think about it, it cant "blow up" because the pressure is being released by the output of co2 (via the airstone, or through aa powerhead). I also put a package of Knox gelatine in my mix for the yeast to feed on, it helps it last longer
 
First off...I meant plastic juice bottles...I have heard some stories about some "explosive" behavior from these setups, but the plastic juice bottles are much more rigid than 2-liter soda bottles.

You might want to put a check valve on the line, then you can just leave it in the tank until it runs out...this will keep it from sucking in tank water when it's empty.
 
I've found DIY CO2 varies wildly depending on your recipe. F'r'instance, adding more yeast produces CO2 faster but also burns out quicker; the amount of sugar will limit the life span of your batch.

The recipe I was using when I was doing the 2-liter gig (I've switched to the Hagen System) was this:

- Fill 2L soda bottle to within 4 in of top with warm (not hot) water.
- Add 1/2 c of sugar.
- Aerate by either inserting an airhose or capping the bottle and putting some AC/DC on the stereo and shaking the beejesus out of it.
- Add 1/4 t yeast and a pinch of baking soda.

This would usually last about 3 weeks. I'd shake the contents, drain out half, refill with warm (not hot) sugar water. This would cause the yeast to multiply and kick the process off again.

Every so often I'd make a fresh batch from scratch.

HTH
 
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