"Morten" wrote in message
...

"Elaine T" wrote in message
m...


HCl fumes badly in concentrated form, and I think I remember some fumes
from dilute HCl (haven't handled the stuff in a while). Same with
acetic acid for that matter. Wouldn't you tend to acidify the fishtank
some with acid fumes, or are they not concentrated enough to matter?

HCl does indeed fume a bit and so does the Acetic Acid (Vinegar), but the
acid is inside the ballon / drip bag inside the first container, and the
only way out of there is via ahose leading to the main reactor where it
gets
neutralized / reacts with the baking powder and because you only draw off
the gas you should be fine. If you're to worried you could send the CO2
gas
through a bubble counter / water scrubber, that will take care of any
stray
HCl / Acetic Acid molecules that might be in gas form inside the main
reactor.

So in fact there will be 4 containers, one which is open at the top with
water in it with a hose comming out of the bottom, the hose leads to the
acid in ballon container on the outside of the ballon, the hose from the
ballon goes through the bottom of the acid container and leads to the main
reactor which also contains the baking powder solution. From the main
reactor a small hose goes through a smaller container filled 2/3 with
water
so that the co2 has to bubble through the water and out via another hose
above the water level and into tank diffuser / co2 reactor / valve /
whatever...

Or you could bubble through a concentrated solution of NaOH which does not
fume and would last a lot longer than a pure water bubbler. A flask full of
NaOH pellets backed by some MgSO4 pebbles (to remove moisture from the gas
before it contacted the NaOH, which is hygroscopic) would also work.