Re: CO2

[Dan Dixon <dandixon at mac_com>]

Allen and Sandra at allensandra at boatmans_com wrote:

> Secondly, I came into possession of a CO2 system for a greenhouse.  (20lb
> and 50 lb tank, plus timer, regulator, solenoid, and emitter/injector) and I
> was wondering if that could be used for an aquarium?  If so, to what should
> the SCFH be set?

The emitter isn't any use for aquarium injection, but the timer and solenoid
might be usable if you want to automatically turn CO2 off at night. Probably
overkill though. If your KH is stable you could also use the solenoid with a
pH controller. Sell the timer and emitter (and solenoid if you're not going
to buy a pH controller) and use the money to buy the other components you
need. You will need either a diffuser (high-pressure), or a fine resolution
metering valve (low-pressure) to control the flow down to aquarium levels.
Some people also use a needle valve with high-pressure systems to prevent
end-of-tank dumping. If you go with a low-pressure system you'll need a
reactor, or just inject into powerhead or canister filter intake. Bubble
counter and check valves are optional but handy. Regulator output pressure
will depend on what type of system you build (high or low pressure),
typically between 5 and 30 psig, but it could be more or less.

Hoa Nguyen has a good diagram of a typical low-pressure setup:

http://www.geocities.com/Heartland/Hills/2637/

Dan Dixon