Issue with PH pens

[judgefudge1]

Ok so my issue is that i have two ph pens, A Milwaukee i brought about 5 years ago that hasn't seen much use only 1 grow.

And a new ET pen that i brought a couple days ago.

 

So they have brand new batteries and new buffer solution 7.0

 

The first picture is them in the buffer solution at 7.0

 

and the second is in tap water (brisbane south close to the cbd)

 

So i wanna know what ph pen to use because there is a difference of 1 ph between the pens, if any 1 lives in my area and knows the ph that would probably help the most.

 

or any ideas because it is doin my head in

Edited October 25, 2012 by judgefudge1

[judgefudge1]

should i buy another buffer solution at a different range?

[El Gato]

Or buy another pen.

Could 3 pens show different?

Edited October 25, 2012 by El Gato

[judgefudge1]

So i put some PH down in some water and both pens tested 2.1ph

 

But then i put em in plan tap water and they differ like WTF

[STONEDAJ69]

By only using one calibration fluid you're not ACTUALLY calibrating the probe.

 

You need to use two, my meter came with 6.86 and 4.2. Use the higher first, then the lower.

 

Twist the screw in back til it reads correctly in each solution.

 

CLEAN THE METER BETWEEN CALIBRATION SOLUTIONS.

 

If there is still a read error, one of your probes is fucked. Buy another one and play the elimination game to find out which.

[Frazz]

what about you get some Flairform PH colour change liquid and use that as a guide read water PH, compare with the pens... its a cheap option

 

[ants]

Also would help getting some flairform 'electrode cleaner' especially for your old meter. And like -5150- said, you need ph 7 and 4 to actually calibrate.

[Faith]

Hiya Judge - I think this post would make a pretty useful sub-forum - I'll be coming back if I need Info. I'm pretty green and this info in this kind of format is pretty valuable. Just a thought anyway

 

Peace to yas. v

[-SLIPPER-]

IMO The cheap analog meters that need to be calibrated using a screw never seem to be accurate,

no matter what calibration solutions are used.

The digital meters that auto calibrate and recognize buffer solutions are way more accurate.

 

A good tradesman doesn't buy shit tools.

 

Just my opinion.

[judgefudge1]

thanks for the constructive help slipper, not every one can afford top of the range tools and we have to make do.

 

Just my opinion