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



You're right Cynthia, I missunderstood your message the
first time I read it. I had the open/close  right but the
the set points backwards. 

The controller switch is ON (closed circuit) when the pH
reaches the upper set point, which energizes the
electromagnetic coil in the solenoid and pulls open the
mechanical valve in the solenoid. CO2 is released, which
lowers the pH. When the pH drops to the lower setpoint, the
controller's switches to OFF (open circuit) which allows
the spring in the solenoid to close the mechanical valve.

Thank, Cynthia,
sh

--- Cynthia Powers <mscyn at earthlink_net> wrote:

> 
> You got that backwards. . . the controller turns
> the solenoid on (open) when the pH gets above the set
> point, and turns off
> (closes the solenoid) when it gets below the set point.
> 
> 
> If it turned on when it got below a set point, it would
> turn the co2 on,
> thus lowering it more, then it would never turn off.
> 
> 
> On 11/19/05, S. Hieber <shieber at yahoo_com> wrote:
> > >
> > > 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.
> >
> >
> >
> >
> 
> _______________________________________________
> Aquatic-Plants mailing list
> Aquatic-Plants at actwin_com
> http://www.actwin.com/mailman/listinfo/aquatic-plants
> 


* * * * * * * * * * *
Opening both barrels at once:

The Grand Opening 

You can find the winners and all the other terrific entries in the 6th Annual AGA Aquascaping Contest here:

http://showcase.aquatic-gardeners.org


And the other Opening:

In response to repeated requests from aquatic gardeners, the AGA has opened forums for the benefit of the community:

http://forum.aquatic-gardeners.org/
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