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Re: CF Lights and pH probe interference

Sorry, I hit send before I typed my message, so the quote appears but not my 
response.  Jerky trigger finger on the send button.
Electronic ballasts use a switching power supply circuit that is, from a 
Radio Frequency standpoint, very "noisy."  They are actually little radio 
transmitters, and can interfere with televisions, radios, and other 
electronic devices.  There would be no surprise that they might interfere 
with a sensitive instrument such as a pH probe.  The solution might be just 
to turn off the lights while you're doing pH measurements.  A more elaborate 
solution would be to go into the ballast circuitry and install RF filtration 
and bypass capacitors to ground out RF interference.  This is going to 
require that you open up your hood.  I don't know your electronics 
background, so I don't know if I'm talking over or under your head, but 
you'll need to install 0.001 mfd ceramic bypass capacitors of an appropriate 
voltage rating (600-1000 volts) across each of the electric wires feeding 
into and out of the ballast circuitry.  It would also help to replace the 
2-wire power cord with a 3-wire cord and electrically fasten the green wire 
of the cord to the metal case of the hood, to provide for a ground 
connection.  Another thought is to pull out a sample of aquarium water, carry 
it to another room, and do your pH testing there.

> I cannot use my PinPoint pH meter at the same time my CF lights are on - the
>  readings jump all over the place, sometimes into negative numbers!  I
>  understand it is interference from the ballast (mounted in the hood in
>  between the lights), but I am at a loss as to how to avoid the problem.   I
>  have even considered getting a small wet/dry to place the pH probe in the
>  sump!  Of course, this is only a 30G aquarium (X-tall), and a wet dry is
>  likely overkill.