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Re: Aquatic Plants Digest V2 #936



> Any suggestions regarding how I can prolong the CO2 output would be greatly
> appreciated.
> Ken Guin
> kenguin at erols_com

Unless your yeast batch is actually clarifying, then it should still be
producing CO2 well after one week.  When I hear this story I always
suspect a leak.

Blow into the airline and see what happens.  After a little give right at
first to pressurize the bottle there should be *no* give.  If you can
force any more air in, then it leaks.  This is really not as easy to tell
as it might sound.

Alternatively, when the CO2 is running, block the outlet with your thumb,
or with a valve and hold it for a few minutes.  When you let go there
should be a big burst of CO2.  If there isn't, then it leaks.

Can anyone else think of good ways to check for leaks?

What could leak?  Make sure the cap's on tight.  If you removed or damaged
the washer inside the soda bottle cap, then the cap may not be sealing to
the bottle.  If you used silicone sealant you might check and make sure
that the silicone actually bonded to both the cap and the airline
connector.  It sometimes won't get a good bond and it is really not easy
to tell.  If you use old vinyl tubing that has hardened, then maybe it
isn't sealing to your connector.  Try new vinyl or silicone tubing.

I avoid several of those problems.  I make the outlet in the thickened
shoulder of the bottle, below the cap.  Use a 1 1/2 inch long piece of
rigid airline tubing and drill a hole in the bottle just big enough to
insert the rigid tube.  Find a nut big enough to slide over the tube and
slather epoxy cement in it and on one side of it.  The nut is used to
reinforce the seal.  Fit the tube into the nut then into the hole in the
bottle.  Press the nut firmly against the bottle and make sure the epoxy
forms a continuous bead at the point of contact between the nut and the
bottle and between the bottle and the airline. There should be enough of
the rigid tubing outside the bottle that you can grasp the tubing (not the
bottle) when you connect it to an airline.

I also use a couple 1-gallon sports drink bottles that have a broad, flat
lid that seals without a washer.  I used a brass tubing coupling, inserted
that through a hole in the lid and secured it in place with nuts from both
sides, sealing the outer contact with a rubber gasket. Then I epoxied
(that's a verb?) rigid plastic airline inside the brass fitting. I'm not
happy with using brass here, but I haven't found the couplings in
stainless steel or plastic.

Don't use cyanoacrylate glues (super glue) in the place of the epoxy.  It
doesn't last.

Some people replace the soda bottle lid with rubber one-hole stoppers and
run rigid line for the airline connection through the stopper.  I haven't
done that, mostly because I've used rubber stoppers for other things in
the past only to have them harden over time and stop sealing.  That would
take a couple years, though.

If the yeast really isn't producing CO2 any more, then maybe your solution
is contaminated.  When you make a new batch be sure that the bottle and
all utensiles are clean and sterile.  The only time I really had a good
yeast batch stop that early it was because I let aquarium water siphon
back into the reactor (what a mess).  That contaminated the whole thing
and produced slime instead of CO2.

Roger Miller