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Re: DIY CO2 bubble size
On Mon, 20 Mar 2000, troi wrote:
> The instructions on the KRIB say I should use about or two bubbles per
> minute. I am using a glass bead, low back pressure air stone on the air
> line, but cannot get "one or two bubbles per minute." Without an in-line
> air valve, I get a nearly steady stream of small, not tiny bubbles.
> With various adjustments, I got bursts of bigger bubbles every 2 or
> three seconds, streams of tiny bubbles, or very slow, but steady,
> streams of small(vs tiny) bubbles. The instructions don't say what size
> bubble should escape once or twice a minute, or if a burst of bubbles
> from an air stone counts as one whole bubble or several bubbles. Iam
> confused and concerned.
I think the instructions are referring to bursts of bubbles from the end
of the airline leading into the tank, without any kind of air stone or
nozzle on the line.
> I settled for the smallest, slowest stream I could manager and await
> further clarification.
Your valve doesn't regulate the rate that the yeast produce CO2. When you
use a valve on the line you are forcing the excess CO2 to leak out of the
system without getting to your tank. If you're lucky that will be a slow
leak and you'll just lose the CO2. If you aren't lucky then pressure will
build up in the generator until it ruptures. That's a *big* leak. And a
> The Krib article also mentions upping the efficiency and diffusion by
> sticking the line in an intake or a diffuser. I am using a Rio 200
> powered with prefilter and a small Aquaclear. CAn I just stick the
> airline in the box of the Aquaclear or run it into the Venturi input on
> the Rio? Of am I ok on a forty gal. currently lightly planted tank with
> just the clumsy air stone? Should I go to a higher backpressure?
Actually, you should probably replace the Aquaclear with something else;
the turbulence it creates will drive a lot of the CO2 back out of the
water. Don't connect the CO2 line to the venturi on the power head. That
creates a lot of suction and can collapse your generator and pull the
sugar solution into your tank.
Your best bet is probably to find some way to hold the CO2 outlet below
the intake of the powerhead so that the bubbles get sucked in. Don't get
the CO2 outlet too near the powerhead intake otherwise (as with the
venturi) the suction can collapse your CO2 generator and suck the sugar
solution into your tank. Keeping the airstone on the outlet will help
prevent that, but my experience is that things tend to grow on an airstone
used for CO2.
> Do I have too much or too little to start with? I take it I can adjust
> appropriately as I monitor my pH later.
I can't tell how much you have. The CO2 production rate starts out high
and drops rather quickly. You might have to start with too much in order
to have just enough after the first few days. You can't actually adjust
the rate easily without losing CO2 and/or taking the risk of rupturing the
CO2 generator. It's best to regulate the CO2 output by using more
solution to increase output, and less solution to decrease it.