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Re: Adjusting and Dosing DIY CO2


Getting the CO2 to be mixed only when the lights are on is easy, I have the
CO2 tube going directly into a Duetto filter (which has an air intake) which
in turn is connected to the timer of the lights. It does a great job at
mixing the CO2 up and just lets it bubble out to the surface when the power
is off. There are various powerheads that also have an air intake, I just
use the Duetto because I also use it for chemical filtration.

Adjusting the rate was a little harder and required a little more DIY time.
You can just use a gang valve, restrict the flow into the tube going into
the tank and open slightly one that releases the rest of the CO2 into the
air. I did this at first and nearly had an accident some years ago, I don't
trust this method 100% and it's also a little tricky to adjust.

The method I use today is a single valve to limit the flow and a pressure
release valve to let the CO2 out when pressure builds up. I'm sure you can
find pressure release valves somewhere out there that would be suited for
this purpose. I built mine out of brass on a lathe and mill and made it
adjustable. It's actually a real easy thing to make, I'm sure one could make
it easily out of square brass rod without using a mill but would probably
have to glue the tube to either end if you don't have access to a lathe.
Another idea I wanted to try and never got around to it was to place a T on
the air tube and place a very high density air stone or similar which would
provide enough resistance to still send the CO2 into the tank but would also
let some escape as the pressure rose.

I used to have a nice lid which I made out of brass and incorporated a
pressure release valve, flow valve and tube attachment which simply screwed
onto a coke bottle but my friend would always have an eye on it when he
visited so I ended up giving it to him. I'd like to make one like that again
when I have some time.

If you like I can send you some sketches, I know I have them.... somewhere

Giancarlo Podio

----- Original Message -----

>setting it up in a way that it is adjustable and only releases CO2 into
>the water when the lights are on

How do you do this?