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RE: Pressurized CO2

Hey, hey everyone - no call for harsh language here...
Anyways - I've been looking for a co2 diffuser/reactor, and saw the
unit, but don't know how it operates exactly.  Can anyone explain how it

works?  And why it is a fishkiller???

Derek Johnson
djohnson1981 at yahoo_com

A diffusor works as follows, the CO2 is dispersed into small bubbles by
being passed under pressure through a sintered glass disk.  The sintered
glass disk has very small pores which causes the CO2 to be released as
small bubbles.  The disk must be cleaned occasionally with bleach or the
bubbles will get bigger.  This type of CO2 dispersion mechanism may not
work for larger tanks, unless you put the output under the intake of a
canister or power filter.  See the Krib at www.thekrib.com/plants for
more info on CO2 injection.

As for its fish killing ability, this is actually attributed to
regulator more so than the diffusor.  Some people report that when the
CO2 tank gets low the regulator losses its ability to regulate the flow
of CO2 and the CO2 tank dumps all of the CO2 into the fish tank
resulting in a pH crash.  Unfortunately no diffusor, reactor or
injection into a filtering device that I know of can prevent this
dumping, because it is a failure of the regulator.  There are two ways
around this phenomenon:

1) Don't let the pressure in the CO2 tank get too low.
2) Put a needle valve downstream of the regulator.  This does not
prevent dumping but it does aid the regulator by providing back pressure
and by controlling the dumping to a preset limit.  Thus your pH may drop
but not as far as it would without the needle valve.

I have a regulator - needle valve - Eheim diffusor setup running and I
have let my CO2 tank pressure goto zero without any dumping phenomenon.
I found that the PSI drop with the needle valve was greatly reduced in