pH Controller

To: Aquatic-Plants at actwin_com
Subject: pH Controller
From: George Booth <booth at hpmtlgb1_lvld.hp.com>
Date: Mon, 10 Feb 1997 12:43:11 -0700
In-Reply-To: Your message of "Mon, 10 Feb 1997 12:16:53 EST." <199702101716.MAA16252 at looney_actwin.com>

> From: "Jim Viscosi" <skribb19 at borg_com>
> Date: Mon, 10 Feb 1997 07:05:22 -0500
> 
> I bought an UltraLife pH controller about a month ago.  I notice that
> when I turn the tank lights out at night (3 flourescent tubes), the pH
> reading will instantly jump from say 6.84 to 7.8 for a second,
> triggering the CO2 to come on for about 15 to 20 seconds.
> 
> Anyone have a clue to whats happening here, or better yet, a
> suggestion? This didn't happen in the first week of use.

We don't have the Ultralife pH controller but we do have two Ultralife
temp controllers.  One works fine but the other exhibits much the same
behavior.  When it turns the heating cables on or off, it gets in the
mode of:

1. cycling power causes the temp reading to change
2. the new reading causes the controller to cycle the power
3. goto to 1.

The end result is a lot of relay clicking that I, fortunately, can't
hear.  Really bugs my wife, though. 

I think this indicates a very poor electrical design, i.e., the power
supply is not bypassed properly or something to that effect.  I
suspect this is the reason Pet Warehouse no longer sells them. 

You might try a grounding probe in the water.  The induced EMF from
the lights may be affecting the probe enough to tweak the reading when
the lights go off.  This helped with an older Sandpoint controller
that was acting up.

You also might try plugging it into a surge suppressor, if you suspect
that power surges occur when the lights go off.

On the other hand, we notice even our "good" CO2 controllers
responding to electrical events in the house, especially lights going
on and off.  The CO2 probe circuitry is very sensitive stuff and this
may be the "nature of the beast".  If there is no other result than
the CO2 running for 20 seconds, I would live with it. 

George