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Hi all, I was wondering, in considering setting up a soda bottle CO2 generator: if I have a check valve in the airline, does it matter what level relative to the tank the bottle goes? The tank is about eye level on a bookcase, so it'd be really difficult to put the bottle anywhere above the tank or level with it, unless I put it on the closet shelf near the tank and run the airline around to it. Does it matter where on the line the check vale goes?

From what I've been reading, a wood airstone will probably be ok for my tank. It's 10 gallons, and I'm on a budget until I get a job (at which point I might be moving anyway).

Please help me out with your expertise

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The check valve it there really to stop any tank water from flowing into the CO2 generator bottle. I have my check valves at the top of the tank (out the water) on the diffuser side of the hose. Just a peace of cation you need to put the bottle somewhere it will not get shaken knock over etc. The mixture is toxic to a lot of fish and you do not want it entering you tanks water

Djrichie
"So Long, and Thanks For All The Fish" Douglas Adams

Hi,
I seriously doubt that a wood air "stone" will work with
DIY CO2. The pores in the lemon wood are so small that it
takes a great pressure to force its way through them and
out into the tank. The back pressure could cause problems.

If you have a UGF with a power head you can attach the out
put from the generator to the power head. Actually, the
best way is to use some sort of reactor instead of a
diffuser.

Frank

-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Check valves keep water from flowing backward and down. If the bottle is above the level of the tank then a check valve will do nothing. If it's below the level of the tank then it doesn't really matter where you put the valve just make sure it's pointed the right way. Arrows on the valve point in the direction the co2 is going toward the tank not toward the bottle. Also replace frequently. Co2 is acidic and eats away at plastic. It will destroy the valve after awhile and can even destroy your tubing if it's cheap stuff. DIY co2 is hard on airstones. They clog up easy and you will end up replacing it after awhile. I just get cheap ones for $1.50 a pair and replace about every 6months.

You could probably hook the co2 into the venturi valve opening(air hole on the top of the output) of a powerhead without issue. Don't hook them onto intakes of powerheads or filters if using a flimsy plastic bottle. More than once someone has had their bottle sucked dry and all the co2 mix spread into the tank. Technically it's not really toxic to the fish but the sudden bloom of organisms can use up the oxygen in the tank leading to the fish suffocating. Even if that doesn't happen it will cloud the tank horribly for possibly weeks. Very nasty to clean up.

Thanks for the advice. I'll set it on the floor next to the bookcase then. I ended up getting cheap fine-bubble "discard-a-stone" plastic diffusers.

I don't have a UGF or powerhead. I figure I could put the diffuser under the smaller piece of driftwood so at least some bubbles stay around for longer.

Sham, sounds like you've had experience with cleaning up yeast mixture. I'll be remembering your warning!

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Hi,
Just remember that the longer the bubbles stay suspended
within the water, the more efficient the exchange of
CO2 into the water. That is the reason for the smaller
bubbles. The larger ones fight their way through the tank's
currents and go directly to the surface where they burst
into the atmosphere. The smaller bubbles get blown around
the tank with the tank currents and take longer to reach
the surface, leaving more CO2 in the water.

With DIY CO2 you have a finite amount of CO2 and you want
to make the most efficient use of it. Keep surface
agitation at an absolute minimum. If you can, make the
surface like that of a stagnant pond, no ripples, etc.
That way the surface tension will help retain the CO2
within the water.

The contradiction is that you are using an air stone type
of diffusion, which will rile the water and help eliminate
the CO2 that you are trying to have absorbed. That is
the reason why a reactor is more efficient. With the
correct use of a reactor, none of the generated CO2
escapes to the surface, it is all absorbed.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Frank I agree with you on the reactors, but even the small size reactors cost any where from 35.00 to 55.00 dollars and take up and sizable area and are difficult to hide. With a DIY system you will not generate enough steady flow of CO2 with yeast to use IMO such a costly diffusion system. On top of that you are limited to the size of a tank you can use yeast systems on, by the amount of CO2 gas you can make with yeast systems. So I think that using a CO2 ladder would be a better pick for this application. You know I have both system running, and the largest tank I feel with a single bottle DIY system would be a 40us Gal tank, after that the effects of the CO2 is minimal to the plant's. You can find the co2 ladders on ebay under aquarium diffuser.

How long does the hose have to be to reach the floor to the tank. You do want this to be as short as possible, the CO2 gas will leak thought the tubing. Even with the special CO2 tubing there's still some lose. An while we talking about CO2 gas loss make sure all fitting a seal good, use some aquarium sealer to kind of glue any of those types of joints. The less leaks the better with DIY systems. Something else is your mix, if you add more yeast in will generate more gas quickly but for a shorter time. If you balance the mix right, you can get 3 weeks of steady flow CO2 gas, and we all know constant level in the tank is what you aim for. If you add to much of either you could end up with a tank full the mix, and that not good.

Djrichie
"So Long, and Thanks For All The Fish" Douglas Adams

I don't really understand the need for a reactor unless you've got a really big tank. With my little cheap airstone inside a corner sponge filter and 1 bottle of mix I can dissolve more co2 than my 55g needs. My tank was heavily planted with 6wpg and I had to point the spraybar at the surface to get rid of some of it because it was approaching 40ppm. I never saw a point to making or buying a reactor when I got great results for minimum effort and less than $10.

Well, I have one last question. We have tons of "active dry yeast" (for baking), which I plan on making the first batch with anyway. I've read that this works, it just has a slower metabolism than brewer's yeast. But if I wanted to use brewer's yeast, where would I find it? What kind of store, and in what section?

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