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more CO2 regulators
Forgive me for adding to this thread, but I feel compelled to add a comment.
It seems to me that a pH controller is a REQUIREMENT for any CO2 system to
function reasonably. As long as the water has a reasonably stable kH, a pH
controller will maintain constant CO2 levels. Such a system contains
feedback, and forms a "closed loop" control system. Closed loop control
systems essentially compensate for drifts/inaccuracies of any component in
the system, including the "plant" (the aquarium water in this
case). Without a pH controller, the system is "open loop", and one must
try to adjust the flow rate (splitting hairs) to keep the CO2 (or pH) constant.
At my laboratory, we run gas lasers (including CO2!) and low pressure
plasma experiments by flowing in gasses while pumping. We need precise
pressure and flow rates, and we use quality regulators (Mathesson),
precision needle valves, etc. But most importantly, we use closed loop
control (via pressure or flow controllers). Open loop control simply does
Having attempted to make an open loop yeast bottle system work on my 20
gallon tank, and watching the pH wander all over the place and stress my
fish, I concluded that was was a waste of my time. I bought a Pinpoint pH
controller, and a needle valve and regulator from the local welding supply
store (I have no idea what brands) and an Aqualine Bushchke valve. It has
been running with NO PROBLEMS AT ALL for 18 months.
Of course, when the CO2 bottle gets very near empty, NO regulator can
maintain pressure. You need more gas.
If you are having trouble with an open loop system and think more precise
regulation is required I would suggest you really need a pH
controller. Then I would claim that probably ANY regulator will do the
job. If you are trying to save money, I would also suggest that your time
would be better spent working a part-time job to afford the right
equipment, rather than fighting with a system that is doomed from the get go.
Mark Gilmore, Ph.D.
UCLA Electrical Engineering Dept.