DIY CO2 + dome methode. How to monitor CO2 levels?

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kyazh

AC Members
Feb 28, 2006
129
0
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37
Glendale, Ca
I just made a DIY CO2 system with a 2L bottle for my 29G. Bubbles are still coming slowly even though I made the mixture last night.

2 cups water
2 cups sugar
1/2 teaspoon yeast

I used the bottom of a 16oz water bottle as a dome to capture the CO2 bubbles. Now I have a few questions.

1) The CO2 is trapped in the dome, and sometimes I see my fish going in there and going for air in the 'surface' of the water. Is this going to harm the fish?

2) How does the water make use of the gas? If my mixture stops producing CO2, will the amount of gas in the dome start to get less and less?

Thanks for any help!
 

Sorab

AC Members
Sep 5, 2007
99
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London UK
I expect that if you have labyrinth fish or other air breathing fish that the Co2 wouldnt be good for them. I dont know how to solve that though. You need a net or something to stop them going in. I used that method but never noticed air breathing fish taking in Co2.
The Co2 disolves in the water so yes the amount of gas in the dome would get less if your mixture stopped producing C02.
 

Ajordan

Se?or Member - Get it?
Nov 21, 2006
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Massachusetts
The amount of gas as a volume may not decrease by any appreciable amount. The concentration of CO2 in the 'bubble' may decrease though. O2 and other gases absorbed in the water may exchange with the bubble much like at the surface of the tank. You may want to pick up a 'drop checker' to monitor the CO2 level in the tank. You could also estimate the CO2 level by comparing the pH and KH of the water (I found that it was better to know these levels before CO2 is added...)
 

midiamin

MidiAmin
Jan 29, 2005
592
0
16
San Francisco
I just made a DIY CO2 system with a 2L bottle for my 29G. Bubbles are still coming slowly even though I made the mixture last night.

2 cups water
2 cups sugar
1/2 teaspoon yeast

I used the bottom of a 16oz water bottle as a dome to capture the CO2 bubbles. Now I have a few questions.

1) The CO2 is trapped in the dome, and sometimes I see my fish going in there and going for air in the 'surface' of the water. Is this going to harm the fish?

2) How does the water make use of the gas? If my mixture stops producing CO2, will the amount of gas in the dome start to get less and less?

Thanks for any help!
If you want a faster bubble, add another 1/2 teaspoon of yeast when you refill. Total: 1 teaspoon
 

Squawkbert

Senior padder
Oct 3, 2006
3,417
2
38
60
ST.L area
www.aquaticplantcentral.com
^ temporary effect only...

1) You're wasting sugar - at that ratio, you're going to make enough ethanol to kill your yeast loong before the sugar has been exhausted. Use a 3:1 Water:Sugar ratio next time (3C water, 1C sugar).

2) The amount of yeast you add doesn't matter a whole lot as it will reproduce via fission until it reaches a maximum sustainable level. This level is most likely determined by the surface area of the water/gas interface in the bottle (short, wide bottle=larger sustainable population).

3) If you really want to know how much CO2 isn dissolved in your water, get a drop checker, 4dKH solution & Bromothymol blue indicator (search these forums for any of these terms for more info).
 

kyazh

AC Members
Feb 28, 2006
129
0
0
37
Glendale, Ca
alright, I got some bubbling action after a day, I added water all the way up to below the curve on the 2L bottle. I also added another 17watt T8 light. So now I have 4x17w T8's, CO2, and I'm adding 'plant food' once a month from a bottle. How long will it take for me to see improvements in plant growth ?
 
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