# Big or small bubbles?



## Blaxicanlatino (Jan 28, 2008)

I have a DIY yeast CO2 generator hooked to a air tube that leads to the aquarium. My problem is that when the a bubble emerges from the tube, its a big bubble. I want small bubbles so that they wil dissolve better. I dont want to use an airstone because an airstone tends to get a clear film over it. Is there anyway i can make small bubbles that will not get a clear film on it? Tanks


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## Tyyrlym (Jun 1, 2008)

It's a function of the tubing. I don't think you're going to be getting smaller bubbles out of just the tube. The residence time of a bubble is also far too short to get much out of it. I've seen some ideas for DIY reactors that would be a better solution. Alternately you can just make the airstone a maintenance item and replace it regularly.


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## Blaxicanlatino (Jan 28, 2008)

I see I see. but what about putting a small piece of sponge in it? or maybe even a wooden one?


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## Tyyrlym (Jun 1, 2008)

Anything that will break up the bubbles will likely work. A sponge or wooden airstone will serve the same purpose as a ceramic one. The downside is that the residence time of an unrestrained bubble still sucks. You'd be better off with something to increase the contact time between the bubble and the water.

In fact I'm a little curious about the film you mentioned. Is it purely a consequence of running CO2 through a stone? I ask because I had an airstone in my tank for 3 months and never had a problem with it running air.


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## Blaxicanlatino (Jan 28, 2008)

i think i know what your saying: the co2 solution is siphoning into the aquarium. Well i have a check valve. And Ive had the white film even back when the same tube and airstone was hooked to a simple air pump and i still had the clear film on the airstone. IVe heard of others on this forum that had the same problem. REsearch on this has shown that there still is an unknown reason for the clear film. When you say to increase contact time, do you mean to shorten the tubing?


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## onefish2fish (Jul 22, 2008)

the clear film is prob. yeast or sugar build up. increasing the contact means the amount of time the bubble is in the water to be more efficient. the longer the contact the more co2 that gets into the water rather then a bubble floating to the surface and popping releasing the gases.
the order of most efficient to last- a diffuser would prob. be the best way of going, then would prob. be having the bubble get sucked into your filter first, then an air stone, then just having it come straight out of the tubing. im sure there are other methods in between.


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## Tyyrlym (Jun 1, 2008)

The CO2 bubble, if left to just float up, is only in contact with the water maybe 2 or 3 seconds before it surfaces and releases that gas into the atmosphere. That's very little time for gas exchange to occur so very little of that CO2 is getting into the water. It's better than no CO2 injection but not by much. What you want to do is use a device that maximizes the amount of time the bubble contacts the water. The longer it does the more gas makes it into the water.










As you can see the bubbles enter at the bottom and then have a long tortuous path up and out of the device. This maximizes contact time between bubble and water. There are other, more complex designs you can buy and simpler ones you can make. Personally I like this design as a sort of middle of the road solution.


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## Blaxicanlatino (Jan 28, 2008)

i just have a bell like hold by cutting a water bottle in half then putting the tube through the cap, that way when the bubbles emerge, they are trapped in the bottle top.


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## Jessica (Sep 18, 2007)

Tyyrlym said:


>


Do you have a link for where I could find this?


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## Rikesh (Sep 23, 2008)

Blaxicanlatino said:


> i just have a bell like hold by cutting a water bottle in half then putting the tube through the cap, that way when the bubbles emerge, they are trapped in the bottle top.


I agree. I use a simple DIY bell made of a small plastic soda bottle.


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## Tyyrlym (Jun 1, 2008)

Does the gas dissolve quickly enough or do you get bubbles leaking out around the cup?



> Do you have a link for where I could find this?


Most online fish supply stores have equipment like this.


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## Blaxicanlatino (Jan 28, 2008)

Ok so i add an airstone to the tube to make smaller bubbles but as soon as the small bubbles are trapped in the bell, the break and fuse into one big bubble. Is this ok for them to dissolve in this form? I know that smaller bubbles tend to dissolve faster than that of larger ones. The larger bubble will break off once it gets a certain size and break a piece off about every 10 min


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## Tyyrlym (Jun 1, 2008)

Well you didn't mention the bell to begin with. If that's the case the bubbles coming out of the tube make no difference, your CO2 diffusion is happening in the bell. Ideally you don't want any bubbles escaping the bell. You should look for a larger bell, one that will expose more of the bubble's surface to the water to allow more rapid diffusion. If you're using a part of a water bottle look into using the top of a 2 liter bottle. More surface area means better diffusion.


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## Blaxicanlatino (Jan 28, 2008)

ok but should i worry about the bubbles being smaller? Im also trying to bury the bell under the gravel. I will have some pics of it today.


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## Tyyrlym (Jun 1, 2008)

I'd leave the bell out where you can see it. No, bubble size doesn't matter since the bubbles are going into the bell. The second they're in the water by themselves is inconsequential because of the bell.


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