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Re: Aquatic Plants Digest V3 #28
>Date: Thu, 15 Jan 1998 15:00:49 -0800
>From: Stephen Pushak <teban at powersonic_bc.ca
>I think another approach would be to examine the pH changes which occur
>in a tank with continuous CO2 injection during the day versus those of a
>tank where the CO2 injection is stopped at night.
I can't run such an experiment because all our tanks are on controllers.
What about this for a alternative...
The pH controller turns off the CO2 when the pH has fallen to 6.95 and turns it
on when the pH has risen to pH 7.05. This corresponds to a change from 16.85
mg/l to 13.40 mg/l at 5.0 dKH. Knowing the exact water capacity of the tank and
the time between the controller going off and on, I can determine how many
milligrams of CO2 was used in that time period. By tracking the controller
cycling times over a period of a day, I can determine the difference in usage
caused by photosynthesis.
>Why not measure directly what you want to know when that's simple? ;-)
If only it were ...
OK, can anyone think of a simple way to track the controller cycles? I would
need a computer (got one near the tank). I can plug a 6v power supply (Discman
power unit) into the controller so that I have 6v when it's on and 0v when it's
off. The power supply could even control a relay to provide "open/closed"
actions (kind of like joystick buttons...). I can program. What would be a good
computer port to connect up to? What would be the programming trick to sense
the voltage or closure? I used to have an old computer with MS-Basic that could
do this in a flash. Now I only have a sophisticated Pentium thing with either
Visual C++ or Delphi.
If you have some suggestions, send to booth at frii_com.