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I recently started diy co2 and need some help. I have the normal 2ltr bottle etc...

I use an old gravel vac as the diffuser.

A pic can been seen here. http://community.webshots.com/photo/121912599/252132334vBafAn

Sorry about the quality, it was just a quick pic.

I am getting bubbles coming out of the tube but im only gettin one large bubble in a large period of time.(about 30-60secs) is this because im not using an airstone.

When the bubble comes out of the tube and rises up into the gravel vac it gets to the top of the vac then pops. I dont think this is right. In the gravel vac the water is being replaced with the CO2 gas. is this right? which i dont think is right either because the bubbles needs to diffuse slowly into the water right?

(I hope the above made sense)

Any thoughts?:%)

Large bubble out of the tube every 30 sec to a min...but are you getting smaller bubbles coming out of the airline into your diffuser @a faster rate?

If I remember correctly I was getting a bubble a second or two coming from the airline, but then the large bubble from the diffuser would come ever 30 seconds or so ....

What mixture are you using?

^_^
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i would run the air line well i do works great even with a bio wheel into the filter when the bubble hits the impeller it gets smashed into tiny bits more co2 gets into the water looks better also. If you wanna no how many bubbles you are geting put your ear on the glass you can hear them get smashed i use suger water half and half yeast. change it once a mounth every 2 weeks is better but my plants grow to fast.

nitro:
The large bubble is indeed because you're not using a diffuser. For a given volume of gas, smaller bubbles have a larger surface area. Since the objective is for the CO2 to absorb into the water column, smaller bubbles are desired. They will absorb much faster because there's more surface area between the CO2 and water.

You are partially right in believing that your gravel vac head is not the way to go. It's not the most efficient/expedient way to do it, but it does work. Note that the collected gas will eventually diffuse into the water column. Passing the gas through a submersed powerhead or glass diffuser (smaller bubbles. see above) will hasten the process. If you took a pH test of the water within the vac head, you'd find it low. You want that water to mix in with the rest of the water. Water movement and/or a large exchange area will acheive that. Consider removing the vac 'snoot'. Just use the tube. This will give you a larger area of water exchange between the carbonized water in the vac head and your tank water.
Water movement is acheived by directing water current (flow) into the vac head.

-Wayne

if you can tip your gravel vac on its side it will give the co2 more surface area to dissolve into the water. then the open top will act as a regulator for the size of the bubble. this article talks a little about what i mean. you can still use your gravel vac to trap the bubbles, but you need to keep the bubbles trapped for as long as possible in order to get a good concentration. obviously you don't have to follow their directions to the letter, but just to give you an idea of what you can do with your gravel vac and diy co2

Last edited by moondog at 30-Jan-2005 14:22

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