Diy Co2 Bell

[xautomaticflowersx]

Yesterday I made a DIY diffusion bell for my second attempt at DIY CO2 (the first attempt failing was down to the seal on the bottle lid I think... leakage) to see how I get on with it.
To make it I basically used:
A 20ml plastic medicine cup (the sort that comes with cough syrup so that you can measure out your dosage)
A suction cup
A pair of scissors
Some aquarium silicone sealant (which I later scraped off because as it dried it separated from the suction cup and the medicine cup and didn't have enough elasticity)

I cut a 'V' shape out of the lip of the medicine cup, wedged the suction cup tightly into the 'V' shaped crevice and smeared lots of silicone sealant around it to help keep the suction cup in place. Once it's dry (though I got rid of the silicone since it didn't have enough 'give' for the flattening movement of the suction cup) you just attach the little upside-down medicine cup to the inside of the glass about halfway down and run the airline from the DIY CO2 bottle underneath it so that the bubbles of CO2 that travel down the tubing get trapped in the little 'bell' to be slowly diffused into the water.
So I put the whole thing together at about midnight and this afternoon I checked the levels in my tank. I have a pH of 7.2, with 10 dKH... I think this means I have around 19ppm of CO2. So it obviously works! Plus it can be hidden neatly behind my filter. I'm slightly annoyed that the only silicone airline I could get was bright blue... not terribly discreet! Still, never mind - that can be replaced at some point

 

[Ptarmigan]

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[Jen]

That looks like it works perfectly for you!

I'm not sure how true this is, but I have heard that silicon tubing is the worst to use with CO2, as it reacts very easily, and can get very hard and brittle. Again, I'm not sure how valid that that is, but maybe someone else can verify for me.

 

[kenneth_kpe]

Jen is right ! However silicone tubing wont crack and become brittle over time, its vinyl that does that, silicone however is highly permeable to co2

 

[xautomaticflowersx]

Aaah right... it's interesting to know that. All of the DIY articles I read suggest that silicone tubing is better to use than standard airline as it lasts longer. Standard airline is the one that goes brittle. Obviously specific tubing designed for use with CO2 would have been ideal, but silicone and standard plastic airline are all I could get hold of at the time.
The tank I'm using it in is only very small... it's 24x8x8 inches, which equates to about 6.6 US gallons. With a 2litre bottle feeding into the tank my CO2 levels would probably be toxic given the small water volume if I had very efficient CO2-specific tubing! So in this particular circumstance it's probably just as well I'm using silicone tubing.

 

[Ptarmigan]

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[Jen]

The CO2 will also permeate out the tube outside of the tank. depending on how long the tube is, you could have some substancial loss.

 

[Ptarmigan]

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