Calibration fluids

[george]

Are the calibration fluids used for pH probes (such as the ones from the RK2 power buy) reusable? I know they have shelf life, but can I put it in a bottle and re-use it to calibrate or is it done shortly after I open the packet (i.e. does it oxidize or something)?

For that matter, how often should I recalibrate a pH probe as a matter of general maintenance?

 

[xyzpdq0121]

I think it can be reused upto the shelf life. I have stored some in ziplock bags and it still measured right a month later. I would use something different then a ziplock if I saved it again though.

 

[schwaggs]

As soon as you open them, the pH starts to drift. You can try putting it in a sealed container but you will never know how accurate they are the next time you use them...

 

[george]

Anyone know what chemicals are in them? Or is it written on the side of the packet? That might help me figure out the best way to inhibit the pH drift as much as possible.

 

[jmaneyapanda]

come on George, they cost like a buck each. You should only ahve to calibrate less than once a year. pony up.

 

[george]

jmaneyapanda;35982 wrote: come on George, they cost like a buck each. You should only ahve to calibrate less than once a year. pony up.

Well, nobody mentioned that part anywhere. :tongue2:

I know they're cheap, but if I had to get them every month, then it becomes a pain in the ***.

 

[cameron]

Sam has them for a $1 no shipping if you stop by or just have Brandon deliver them to you.

 

[FutureInterest]

George;35959 wrote: Anyone know what chemicals are in them? Or is it written on the side of the packet? That might help me figure out the best way to inhibit the pH drift as much as possible.

Yes it is written on the sides of the packet... here yah go:

Pinpoint pH 10.000 - sodium carbonate, boric acid and water with antimicrobial added.

Pinpoint pH 7.000 - phosphoric acid, potassium hydroxide, sodium hydroxide, and water with antimicrobial added.

 

[mwitten]

FutureInterest;36006 wrote: Yes it is written on the sides of the packet... here yah go:

Pinpoint pH 10.000 - sodium carbonate, boric acid and water with antimicrobial added.

.
.

Boric acid... Borax. There is a good intermediate standard you can easily make with Borax that I used regularly as a general test to see if I have drifted much, before I go to the full calibration system. Oh, and I usually buy the bottles of calibration fluid... I hate those dumb packets!

For the Borax solution, see:

http://web.archive.org/web/20021015005420/www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp">http://web.archive.org/web/20021015005420/www.animalnetwork.com/fish2/aqfm/2000/feb/bio/default.asp</a>


Also, for a bit more than you want to know on the subject as a whole:

[IMG]http://www.reefkeeping.com/issues/2005-02/rhf/index.php">http://www.reefkeeping.com/issues/2005-02/rhf/index.php</a>

-Mike