# Yeast based CO2 generator doing anything?



## ColdServings

I've put together a DIY yeast based CO2 system, but I'm wondering if it's not a waste of time.

I've got a moderately planted 29 gal tank with goldfish.

The system consists of the following:

2 2 liter bottles filled with a mix that starts with 2 cups sugar, 1 Tbs bakers yeast, and enough water to full to the curve of the bottles.

A 24 oz pop bottle used as a gas separator/bubble counter (I've got a few inches water in the bottom and the end of the tube that comes from the yeast bottles ends below the surface so incoming CO2 bubbles up through the water before moving on.

Instead of using an airstone, filter intake, or homemade reactor I simply purchased a commercially available glass diffuser (cheap enough that I didn't think it worth the effort to DIY. The diffuser includes a check valve.

When the yeast bottles were fresh I was getting about 2 bubbles per second. Just before I refilled one of them, I was getting about 1. Silicone tubing is used throughout.

I use silicone tubing throughout. The only other plastic parts I use are a plastic T to hook up the yeast bottles and an inline coupler to let me disconnect the whole thing simply for testing. All the tubing and plastic is new.

However, I don't see any changes in the dissolved CO2 as estimated by dKH and pH. Whether the system is connected up or not, nothing changes. Furthermore, I don't see any bubbles from the diffuser.

I am wondering if the entire exercise has been a waste of time and what, if anything, I'm doing wrong.


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## Rummynose

First, I would use a different recipe. For a 2 litter bottle use; 1 cup sugar, 1 tbs molases, 1 tsp baking soda, 1 tsp soy flour or protein powder and 1/4 tsp of yeast. This recipe usually generates CO2 for 3 to 4 weeks.

You may also want to double check any connections. On systems with airstones or diffusers, back pressure may cause leaks.

If you use this recipe be careful, I use (1) 2 litter bottle on my heavily planted 55 gallon to bring the pH from around 7.5-7.8 down to 6.9-7.0.


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## Mr. Fish

Make sure you using pretty warm water....
Also make sure theres no leaks... Personally Id get rid of the DIY bubble
counter and just run the tubing from the bottle, to the check valve to the glas diffuser...

To make things less complicated use this recipie:

2 cups sugar
1 Tsp Yeast
98- 103 degree water
mix then seal and you should see the mini bubbles diffusing into your tank...

If you can take a pic for us to help tackle the problem if that doesent work..


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## Rummynose

Before you knock this recipe, try it! I'm not a scientist, but the person who created this recipe is a scientist who studies yeast. The recipe is refered to as the Nyberg method, named after the scientist.
Although it has a few more ingredeints, it's well worth the effort. It produces CO2 that is more consistent, more stable, longer lasting and with only half the sugar.


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## Volenti

I agree with the leak issue, use some soapy/frothy water on all connections to check for leaks.


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## HTN86

I have one of those glass diffusers and I find that they require very high pressure to push the co2 into the diffuser. I'm 100% certain that you have a leak.


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## Mr. Fish

They dont require very high pressure at all....
One way to know if you have a leak is by pressing the bottle togather
while the caps on, if it squezzes togather you have a leak, if it feels like its
hard then you have no leak.

Rummynose Im not knocking that recipie at all, I just knew how it feelt to want
to learn DIY yeast and people hitting you with so many complicated answers
confususing the reader when its not really that complicated at all, infact its simple.

The easiest way I found was this:

64 oz Ketchup bottle
Place a BIC pen cap in the hole of the cap, attach about 2 inches of tubbing
then check valve on the other end, then have the longer tubing run from the other
end of the check valve long enough to almost meet your substrate then attach the glass diffuser.
If you have a HOB filter have it get sucked into the intake with as little water agitation as possible.
Then you should see lil bubbles comming up.... You need two bottles and two diffusers.

Infact I have this setup brand new if you want to purchase off me for a decent price,
if you like it then just shoot me a PM:

http://www.drsfostersmith.com/produ...&Ntx=mode+matchallpartial&Np=1&pc=1&N=0&Nty=1


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## Amazon_Replica

I have no complaints with my DIY Co2. Its 100% custom, but same theory.. I rarely get bubbles out of the diffuser, it dissolves into the water before it can escape. I am using a 3 liter water bottle, 2 commercial check valves, one at bottle and one in substrate just in case.

I have a plastic tube 3" diameter in the tank, Co2 supplied to the bottom of tube, a small gap with holes drilled in side of tube, and a big aquarium safe sponge. above that i have a cap on the tube, and a powerhead sucking water out of the tube. Works well. I also have some plastic marbles to beat at the bubbles caught in the sponge. heres two pics to sum it up. 

And I use in this mix, 4 cups sugar 1/2 tblsp yeast. 1-2 bubbles per second for a day or so then goes to 2-3 bps for about 3 weeks, and slowly rolls downhill back to 1-2 in 4th week. Towards end of 4th week i mix another batch and voila.

You want to add sugar and yeast with no water, shake the heck out of it and mix well. add HOT water from tap until 2/3 of bottle is full, not to curves, 2/3.


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## ColdServings

Thanks all,

I ended up just biting the bullet and ordering a regulator/needle valve/solenoid/bubble counter/tubing combo (and I'll, naturally, be buying a bottle locally unless anyone has a better idea for getting a filled bottle).

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=330192211798&ssPageName=STRK:MEWN:IT&ih=014

OTOH, I'll probably use that with the new 55 I just got for the goldfish and will probably continue to use a yeast system once I convert the current 29 (where my Goldies live now) over to tropicals.


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## ColdServings

Oh, yeah,

In addition to the regulator etc., from a separate source I ordered Red Sea CO2 reactor 500, and the Red Sea drop checker.

At least this will give me a benchmark for any future DIY projects.

As for the yeast system. I think "leak" is probably correct. Using slightly undersized holes and relying on a tight fit to keep things airtight may work all right when there's no significant pressure, but once you put a restriction in the system like that diffuser, things change.

I've _also_ ordered those mini bulkhead fittings recommended in the link from one of the stickied DIY CO2 threads. I'll be making a new set of caps using them.


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## Fortuna Wolf

Silicone is actually rather porous to CO2 and gasses. Since a glass diffuser requires pressure it may be that a lot of CO2 is diffusing out under high pressure through the silicone. I don't think you need to worry about it so much in a system where the line is under a slight vacuum - ie a power filter diffuser since the venturi effect will reduce pressure in the system versus atmospheric. 
Try switching to vinyl or viton or possibly polyurethane hose.


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