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Re: [APD] Ph controllers (was Re: CO2 System)

A pH controller turns on/off whatever device you attach to
it. Fo aquatic gardening purposes, they are normally open
circuit when the pH is above a set point and closed (or ON)
when the pH is below a set point. If you connect a solenoid
to the controller, CO2 will flow only when the pH is below
the controller set point and then will shut down when the
pH is above set point. Since CO2 lows pH, this set up
allows one to automatically control the amount of CO2 in
the aquarium by setting the the contoller set points to a
level of pH that yileds a desired level of CO2 in your
aquarium gien the amount of carbonates in your aquarium.

If it operates 24-7, then CO levels will be maintained
during the evening when CO2 isn't necessary -- but that
won't hurt anything but waste a bit of CO2 which is
relatively cheap.

Otoh, you can skip a controller, which is expensive and
just put your solenoid on your lights timers and then
injectd CO2 only when the lights are on.  Or you can set
the CO2 discharge rate lower and run the CO2 24-7 without
any solenoid. This wastes a bit of CO2 because it flows
evening during the evening.

If you wanted, you could hook the controller to the lights
timer and then the controller will control  the CO2 level
during the lighting period but you will stop all CO2
flowing during lights out.

Whenver you do a water change, if that will change the
carbonate levels, you need to check the crabonate levels
and set the controller setpoints accordingly.

On, for example, the Milwaukee controller, the on and off
set points are 0.1 units apart, so the controller will
maintain the pH between those two points. For example, if
set to 6.6, thenit will add CO2 when the pH get down to 6.5
and stop when it gets to 6.7. 0.2 units is about as much
spread in pH as you'll get running 24-7 without a solenoid
or controller.

So a controller is an expensive and unnecesarry item that
some find convenient.

--- Holly Wagner <holly5dogs at yahoo_com> wrote:

> Hi Everyone,
>   I'm reading this topic with great interest because I'm
> about to break  down and get a pressurized CO2 system but
> being the cheapskate I am I'm  shopping Ebay.  Of course.
>  There's a source there where  systems are avaible for
> $150-$200 with needle valves, solenoids, bubble 
> counters, and ph controllers and some of these systems
> also have  reactors. I'm not famililar with the ph
> controllers.  What  advantage do they give a person?  Do
> they automate anything or  just give you a heads up  due
> to the fact that you have a digital  display that a test
> kit would not give?
>   Holly
> ---------------------------------
>  Yahoo! FareChase - Search multiple travel sites in one
> click.  
> _______________________________________________
> Aquatic-Plants mailing list
> Aquatic-Plants at actwin_com
> http://www.actwin.com/mailman/listinfo/aquatic-plants

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