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Re: more CO2 regulators

Mark Gilmore <gilmore at physics_ucla.edu> wrote:

> 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


> 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
> not work.

Now, could you please explain to us how in the heck your experience at the 
lab lasers relates to aquarium keeping ? Aren't you comparing apples with
oranges ? Aren't the two things (lasers and aquariums) subject to entirely
unrelated conditions/requirements ?

> 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


This is the natural behavior of a yeast-based CO2 system when the kH is too
low. Just add something to increase kH (plenty of recipes in this list). Better
yet, do as I did, replace it with a *simple*, non-controlled, inexpensive
pressurized system. Mine has been keeping pH within 6.5 - 6.7 (diurnal range)
for the past 7 months or so with absolutely zero fiddling and maintenance. 
And the water is at a low kH = 3.0. Of course, before that, I operated a yeast 
bottle for more than one year, and got the pH wanderings you mention. Even a 
dead fish once, and that pushed me into buying the *simple* system. I couldn't,
and still cannot, see why one would need to keep a rock-solid pH. 

Based on my experience I have to disagree and say that, for any *pressurized* 
CO2 system to function reasonably, a pH controller is *not* a requirement.

- Ivo Busko
  Baltimore, MD