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PH Pen Storage Fluid

AverageWhiteBloke

AverageWhiteBloke

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Joined
27 Oct 2009
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Location
Cumbria
Just bought myself a ph pen. Wondered whether or not to also order some storage fluid, I notice that on some of the fluids it says not to be used with pens using gel probes. Wondered why the difference?
 
Keep it moist with what though? I heard deionised water can damage the probe and not sure if any of the chemicals in tap water could cause problems.
 
Just leave a little water in the end cap. Doesn't matter whether its aquarium or tap water. The pH probe in these pens aren't that sensitive to be affected by tap water.

The expensive probes that are used in labs are very very sensitive and cost thousands of pounds. They need to e stored in 3M KCl. But these will be fine so long as they don't dry out totally. They have don't have an internal solution.

Don't worry :)
 
Pm'd so, out of curiosity what happens when these pens are stored before going on sale? How come once they have been wet they need to stay wet but before they can be dry for as long as they want?
 
Good point. Technically speaking they come pre calibrated so they have been wet before. So they should be kept wet. But like you say, when I got mine it was bone dry. Maybe isn't such an issue with such a "cheap" probe. We are taught never let a pH probe go dry. Basically with the lab ones, the solution inside them evaporates and the sensitive electrode dries out.

I wouldn't worry with these ones. I've never even rinsed mine, test then put lid back on with it still wet. It's never gone out of calibration yet and had it 2 months.
 
3M KCl is the ideal storage solution if you can make some of that up. Should be able to buy potassium chloride salt from somewhere.
 
Mine came from hydroponics shop for £45 was thinking of ebay route.can get them for as little as £7 but wont have original package this is to reduce shipping costs from china
I think if you test once a day its money well spent and their also much less hastle than liquid tests
Be aware that some dont have temereature compensation so you might have to let water get to room temp for accurate reading but this is easily tested by testing at room and tank temp to check difference
Its also worth remembering there not all submersiable so dont drop it in tank
Claibration buffers are readily available from ebay too
 
I wouldn't worry about temperature difference. Difference of 10 degrees Celsius only has a difference of 0.1 on the pH scale.

Which is the error on these pens anyway. Readings are always for example, 7.0 +/- 0.1
 
Will be. They are all basically a glass electrode with the copper wire sensor running through.

We use either 3M KCl or if out of it pH 7 buffer in the labs.
 
Hot given mine with no destructions recently, never gave it a second thought. Sounds like a case for wet cotton wool in the cap!
 
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