Help! I need a diy co2 recipe that WORKS!

Thus far I have made at least 6 attempts to do diy co2 for my tanks. The last recipe I used worked the longest, it actually produced for a full week. All recipes I tried before I would only get two days out of if anything. I would really like to be able to go a month before changing the yeast mixture. Does anyone have any good recipes they would like to share?

FYI here's what I did that worked for a week:
1 cup sugar (dissolved in warm water)
1/4 tsp quick rise yeast (I tried regular yeast and it did nothing...the grain size of quick rise is much smaller so I think it just dissolves better)
pinch of baking soda
filled the bottle to the shoulder with warmish water

Maybe I need to be adding something else?


I should mention that I did two bottles at once and yesterday when I noticed one failing I added 1/4 tsp of yeast again to both that one and the other one. That one didn't work at all anymore, but the other one is still going strong from outward appearances. In fact it's doing so well I even have oxygen bubbles forming on the plants in that tank!

 

Hi,
1. I'm making sure the water is lukewarm before it ever touches the yeast.
2. Maybe I could try dumping out half the water, adding more, and adding another 1/4 tsp of yeast after two weeks? If I can get it to last that long?
3. I'll see if I can find it. There's a store nearby that sells winemaking equipment, would they sell anything of use to me?
4. I have a regular airstone inside the intake tube of my hob filter and a hose running into it from the bottle. The filter adds a small suction to it since it is sucking water up past it, so as long as it is producing at all, it usually will come out. This is working splendidly on my 10g, I'm up in the 20's now with the co2 just by using this method alone. On the 32g that I'm having trouble with, I may have to look at using a secondary method as well to get it within range but obviously it's all dependent on producing some co2 first. A few days ago I had it up to about 8 or so using just the filter method, but I'm thinking that I had a leak somewhere that was messing up my co2 production.

One method I was thinking about was this:
Attach the co2 line to an airstone at the bottom corner of the tank.
Near the surface directly above the airstone attach a diffusion bell with a hose coming out of the middle of the top of the bell.
Run this hose into my intake tube of my filter as described above.

This will result in three methods...first the co2 has to rise the 18" of my tank to get to the diffusion bell hopefully resulting in some absorption. Then there will be co2 inside the diffusion bell at all times because the output hose will be positioned low enough that it will not take in any co2 until the bell has filled to a certain degree. Then any excess co2 that is not being diffused by the bell will be drawn into the filter. Any that remains at that point will end up being lodged inside my filter resulting in another type of diffusion bell type thing.

If I can just get it going....I can't wait to try out my experiment to see if it works!

 

Well, I fired up two bottles last night and it's now producing co2 again. But I need to put together my makeshift diffuser system today and see if that gets me up to the levels I want. I would go pressurized if it were free...I just spent $400 on a new tank so no more funds for a while

Good idea about staggering the bottles. Also maybe I need to get my hands on something bigger than a 2L bottle, since evidently it's the alcohol that's killing the yeast. Bigger bottle=more dilution, hopefully longer lasting. Getting the champagne yeast will probably help too.

 

Here's my co2 diffusion system. I'm not sure how well it's going to work yet because I just set it up but I think a lot will have to do with how much co2 I can get producing. Anyway how it works is: The co2 line runs down into the blue bubble wall in the bottom left corner (I could have used an airstone instead). The bubbles come out really small and rise up to the diffusion bell at the top left. You can't see it, but the green hose coming down is coming out of the top of the diffusion bell. This line runs into the intake of my filter. The small amount of suction this produces draws water and co2 bubbles up through the diffusion bell and down through the line and up again into the filter. I'll test later on and see if this increases my co2 in the tank!

 

Yes that's true, yeast and sugar are not free. But as far as time goes, I'm doing all this because it's fun...not because I'm slaving over my tank out of necessity! Plus right now I have lots of time and no money. Paying out a lot of money to have something sit there and look nice with no hassle really doesn't appeal to me, I think I would lose interest at that point. Creative problem solving and experimenting with chemistry is my favorite thing about aquariums! I'm always changing and attempting to improve things and doing it with no money is just another part of the challenge! But that being said, I would rather have pressurized co2 because I want my plants to grow faster and I know that I won't ever be able to devise a system with yeast that will work as good as pressurized will.

I tested this morning and the co2 levels have only raised by a very small amount. Also it appeared to not be producing so well. At further examination I found that my valve is leaking at both inputs. So that would explain a lot of my trouble! Next time I'm in town I need to get a new valve, or maybe I'll silicone this one when I get a chance, but in the meantime some chewed up gum is sufficing to seal it a little better...

 

You have a good eye! Yes you are correct. And yes I've thought about the agitation issue. It's pretty full right now but next water change I'm going to fill it up as much as I can.

nwfishinfool, thanks for the process and tips! I'll definitely try this the next time I need to refill. Which probably won't be long since I'm losing a good portion of my co2 out of my leaky valve right now. Also I have a heater put onto the two bottles I have running to speed up the process and keep my flow running even with the leak, but obviously I know this will make it run out faster too. I'm sitting at around 5 ppm right now which is pretty pitiful, but I'll test again in the morning to see where I'm at. There was a problem today with the intake into the filter too, the hose got dislodged from it's original position last night (due to an overenthusiastic pleco I'm thinking) and it stopped suctioning co2 so it was basically only sitting all night with just the diffusion bell active. I'm anxious to see in the morning if the additional agitation of the co2 due to the uptake hose into the filter makes any difference. My 10g is still doing wonderful at around 22ppm with just a hose running into the intake, and the type of filter that's on the 10g is such that any co2 that does not dissolve immediately when it gets sucked in will get lost to air, so I was pretty impressed that it worked so well on that tank.

 

Ah, the sweet smell of success! My CO2 was up to 20ppm this morning! And that was even after the diffusion bell dislodged a little in the night and the filter wasn't taking in very much co2 anymore because of the angle. But now I have to do a water change....argh. I hope I can get the co2 back up again quickly!

 

I have been adding a pinch of baking soda to each yeast batch to stabilize the pH. My water has no buffer whatsoever....so if fermentation produces acid (I don't know but I'm thinking it does) the pH will drop precipitously. How high is too high (for pH)? I can add more baking soda to add more buffer...if a pH of 8.2 is ok. What about adding other stuff...traces, kno3, etc?

I might be able to get spring water for free...I haven't tested it but maybe I'll get some and see how it tests out. I've held off using it for my tanks because it will be so much colder than the tank at room temperature and I'm doing 50% water changes for ei. Plus it's a lot of water hauling, I would need 20 gallons/week just for my water changes. Anyway it wouldn't be so bad using it for co2.

 

Well my CO2 ran out today on my 10g after one week exactly, so I am mixing up a new batch. I decided to try a few different things this time after doing a little research, here is my mixture I'm testing:

1 tsp yeast (pre-mixed into 104 degree water with a pinch of sugar)
1 tsp baking soda (to add buffer and prevent a pH crash)
1 tsp gelatin (totally experimental...I read somewhere that yeast need protein and gelatin is pure protein...)
2/3 cup sugar (I don't think my yeast mixes before were getting even close to using up the sugar before they died (guess how I knew), plus I read that more than 10% sugar will make a toxic environment for yeast)
1 dropper full of plant food (to add traces and ammonia)
dechlorinator

I dissolved everything in hot water (except the yeast) then added cold water to the rest of the 2L bottle. We shall see what happens!! I'm going to let it go until it runs out just to see how long it will go.

 

The new batch of co2 that I put on my 10g worked too well.... after a few hours the CO2 was up to 84!! So I took the bottle off straight away and did an emergency water change. Then I put the bottle on my 32g tank that I was having a hard time getting into the good zone. This morning CO2 on that tank was at 77! So I shut it off right away and let it drop down to the 20's. I removed the second bottle and now I'm just running the one super bottle on my 32g to see how high it gets. I think I'll add less yeast to the next bottle!!

 

Well it's still a work in progress, but I've figured out a few things. And yes I was basing it on the KH/pH chart. It's not easy to be particularly accurate with that even assuming it is correct, the ranges are quite wide. My tap water is more or less equivalent to distilled water, I add baking soda to bring up the KH and it also brings up the pH of course. I'm not sure what the reasoning is behind saying the chart is inaccurate, I haven't done enough research on it. But I do know exactly what the pH is of my tanks when no co2 is involved, so I can say for a certainty that adding co2 brought it down x amount, if that makes sense. For instance my 10g would normally be a pH of 8.0, but when running that mega bottle of co2 it was down to 6.2.

If the chart is inaccurate, I would guess that it it is at the extremes, because when the chart would say I had 77 or 84ppm, my fish didn't show any signs of distress. But when the chart is telling me I have, say, 7ppm, I still get pearling on my plants.

So what I found out so far was:
1. Only use 1/4 tsp of yeast unless you want it to burn out after three days of mega production. (assuming you have a 2L bottle, larger bottles can be increased proportionately)

2. I've been adding plant food (houseplant) and baking soda to the mix, and my yeast in at least one bottle has not died off yet even though it converted almost all 2/3c of sugar over to ethanol and co2, and I had to add more sugar (dumped out some of the water and replaced to remove ethanol) and it's still going. I tasted it to see if the sugar was gone and it was, so I knew the yeast was probably still alive. Before, I would taste it when it burned out and most of the sugar would still be there, so I knew the yeast died before they finished converting the sugar. I think that 2/3 c is the most sugar you want to add at once, any more than that and it will die before converting it all since so much ethanol builds up and it's just wasting sugar anyway.

3. Running the line of co2 directly into the intake of my hob filters is the best and easiest way to diffuse it without buying equipment and I don't think much is wasted either.

So I'm trying to get away with replacing only one bottle every week on my 32g and I'm not really worried about levels, as long as I can see co2 coming out and I can see pearling on my plants and the pH stays around 7.4 or so I'm happy.

Bottom line is that the correct ratio so far seems to be:

2L water
2/3 cup sugar
1/4 tsp yeast (I use quick rise, it dissolves better)
add plant food and 1 tsp baking soda to add traces and maintain pH

After one week, if it slows down production, taste it and if it's not sweet, dump out the top half of the bottle, dissolve 1/2 c sugar in warm water and pour that in, fill up the bottle again, and keep going. If it is sweet, the yeast is dead, so you have to start over with new yeast.