CO2 reactor question

[havron]

This has really been bugging me lately. Why is it that every time I set up my yeast/sugar/water CO2 reactor with brand new solution and hook it up, water from the aquarium tries to flow UP the tube for a while before CO2 begins to flow down it and into the aquarium? This is really irritating, and I can't seem to figure out why it happens. Anyone know?

 

[Tristan]

You set up a syphon. PLace the water level in the reactor equal to the water level in the tank. If you place it to high it MIGHT do the reverse. It doesn't matter how you have the toobing just as long as the water levels are the same. So basically you just have raise the reactor up until the water in it is at the same height as the aqureium water.

 

[havron]

Ah yes, of course! A siphon, duh. Thanks. I just find it strange that the water in the aquarium seems to somehow "know" that the level of the water in the reactor is lower, lol.

 

[Stefano1]

tristan you still amaze me with your knowledge for someone younger than i am =[

#### when i was your age i wouldnt know half as much as you

 

[Tristan]

hehehehe

 

[havron]

I learned to read before I was 2. :cheesy:

 

[Parasuco]

JERK! j/k

how old r u?

 

[havron]

I'm two weeks short of 21 as of today.

 

[dodecatheon]

But if it was siphoning, it would still need a "push" to get it going. Like Havron said, the water on one side can't "know" what was going on on the other. Where did the push come from?

 

[havron]

I just refilled my reactor, and even though I now have it so that the water level in it is about the same as that in the aquarium, it still tries to flow upwards for a while before the CO2 really bubbles in, though the effect may not be as pronounced. Does anyone know what's going on?

 

[havron]

It just occurred to me: Could the effect simply be a result of the water pressure generated at the level of the tube outlet (about nine and a half inches below the surface of the water)? The effect would then only stop when the pressure that builds up in the CO2 reactor equalled the water pressure at the outlet. Does this make sense? If so, why doesn't this happen when the cap isn't tightly screwed onto the bottle? Air pressure, perhaps?

 

[Tristan]

Describe your set up more

 

[Pyro]

I'm going to take a shot int the dark here. Yeast have to "breath" for this reaction to occur. I would hypothesize that when you first start the reaction the yeast "suck" up the available air from the bottel and the tube creating a partial vacuum that sucks the water back through the tube. As the reaction progresses the CO2 is outgassed and the pressure is equalized, pushing the water back out. CO2 outgassing continues and you get the bubbling of CO2 into your tank.

Just a theory there.

Pyro

 

[Tristan]

I agree with pyro. Yeast acts very guickly and some of the CO2 will disolve into the water. So it would be a while before the balance returns

 

[Parasuco]

Don't quote me on this or anything, i am probably making myself look like a total idiot, but here i'll say it anyways... Don't yeast simply ferment as oppose to carry out cellular respiration? They dont need oxygen, do ferment... Do they? I think i've just confused myself... uuuuuh....


K bye.

 

[Tristan]

Yeast only ferment things under certain condtitions. When dare be no air left

(Edited by Tristan at 1:59 pm on Mar. 19, 2002)

 

[Pyro]

Tristan is correct. Yeast are facultative anaerobes. Or, in plain english, they prefer to grow under oxygen conditions but can grow (less efficiently) under micro/non oxygen conditions by utilizing a fermentation cycle.

Pyro

 

[havron]

Thanks Pyro, yes, this was actually my original theory (that the yeast were "breathing" first), but I wasn't sure if it made sense.

 

[Tristan]

Its still a syphon

 

[havron]

I guess it would be a siphon if I were to allow the water to flow all the way up the tube (which I haven't), and the yeast's supposedly "breathing" before CO2 generation would be what provides the "push" to get the siphon going.