Re: CO2 thoughts

> From: George Booth <booth at hpmtlgb1_lvld.hp.com>
> Date: Thu, 30 Nov 1995 10:54:35 -0700
> Subject: CO2 thoughts ...
> You have 1.8 dKH and the pH changes from 6.5 to 7.  That means the CO2
> concentration goes from 17 ppm overnight to 5.5 ppm in the late
> evening (those plants really suck up the CO2, eh?).  Note in this case
> that when the plants are trying to photosynthesize the most (the late
> afternoon), their source of CO2 is at a minimum.  Bummer.  This is why
> a $$$ controller is good; it can provide all the CO2 the plants need
> by increasing the amount delivered when it is neded.
> [I've never thought about it this way before]

There could be another approach to keeping the pH more stable without 
investing in a controller - increasing both the surface agitation
and the CO2 input.  This would mean that only a small fraction of the 
injected CO2 is being taken up by the plants. Variations in the rate
of uptake of CO2 by plants would therefore have only a small impact on
the pH.  Given that CO2 is about a dollar a pound, and I use about 
a pound a month in my 70G tank, I could afford to inrease my CO2 input
by a factor of 5 before I break even with the cost of maintaining a pH 
controller. (I estimate pH controller operating cost and depreciation to
be about $5 per month).

shaji at nando_net