pH Probe Calibration, is it Really Needed?

[Boomer]

I hope this was helpful and I'm sorry if it turned into a dialog at times.

Nothing to be sorry for Lou. An thanks for the remarks, it was one I was not aware of A number of us here pump up PinPoint, me include, it was nice you can along for the hobbyist :thumbsip:

 

[RobbyG]

<a href=showthread.php?s=&postid=9820701#post9820701 target=_blank>Originally posted</a> by loudell
The reason that probes like pH and ORP will "wear out" has to do with the fact that the internal reference fluid becomes more dilute as time goes on until it reaches a point where the internal fluid is so dilute that you can not calibrate your probes.
Prove it to yourself by comparing a new and very old probe. Check the viscosity of each by moving the internal air bubble.
BTW may peope actually do get 24-30 moths from a PINPOINT probe. I'll tell you how they do it but can anyone guess why??

Some very nice info about the flow, it makes perfect sense. Luckily I had put mine in a very low flow area by chance

What is your feeling on the need for calibration? From what I am seeing, it looks like calibrating the probe every 2-3 weeks may not be needed, just do a good cleaning and calibrate every couple of months. Any thoughts?

 

[RobbyG]

<a href=showthread.php?s=&postid=9828854#post9828854 target=_blank>Originally posted</a> by Boomer
I hope this was helpful and I'm sorry if it turned into a dialog at times.

Nothing to be sorry for Lou. An thanks for the remarks, it was one I was not aware of A number of us here pump up PinPoint, me include, it was nice you can along for the hobbyist :thumbsip:

Guys that was a very informative exchange, thanks.

Loudell your pH probe is premo quality, now please release a stand alone Salinty probe that I can plug into my controller
We have leached your 53ms, so why not go for the whole hog

PS. We have cash

 

[loudell]

pH probe calibration is very necessary and hobbyists do not do it often enough. As the internal reference fluid becomes more dilute inside the blue epoxy the electrical signal also changes very slightly. This means that over time (usually monthly) the reading will be overstated. That is it will read 8.25 when the actual reading may be 8.20. However most hobbists "like" the higher reading and feel that this is a good time to leave everything alone.....

 

[RobbyG]

That's odd, I find mine to be slightly understated. My 8.20 would have read 8.17 if I had not calibrated. When the next couple of calibrations become due, I am going too chart what happens if I only clean the probe.

 

[loudell]

Robbie, when you start to chart differences of a couple hundreths of a pH unit you really have too much time on your hands. Maybe time to start a new tank...

 

[Billybeau1]

:lol:

 

[Boomer]

:rollface: :rollface: :rollface:

Then we have scientists that calibrated their meters to .001 like Millero. If you so much as breathed on the sample the pH would change. 1/10 is plenty good for us. Something not brought up yet All pH calibration solution are not the same/treated equal.

Measuring pH with a Meter
http://www.advancedaquarist.com/issues/feb2004/chem.htm

****A Comparison of pH Calibration Buffers*****
http://reefkeeping.com/issues/2005-02/rhf/index.htm

 

[RobbyG]

<a href=showthread.php?s=&postid=9833044#post9833044 target=_blank>Originally posted</a> by loudell
Robbie, when you start to chart differences of a couple hundreths of a pH unit you really have too much time on your hands. Maybe time to start a new tank...

I wish I could It would be a 2nd Tank plus a Divorce :worried:

 

[RobbyG]

Now 4 weeks later and I did a second cleaning.
Probe was reading 6.88 in 7.00 fluid before cleaning, after cleaning its reading 6.99 so this time I am skipping calibration.

This means after 10 weeks the probe has kept it's calibration and only needed cleaning.

I will report back every 3-4 weeks and see how long it goes before calibration is needed.

 

[Boomer]

Nice to se you doing the Robby

 

[RobbyG]

I know looking at these small differences may seem strange, but it makes no sense to do a study unless one makes notes of even the slightest differences.

At the end of all of this I hope I can say that after X amount of months the probe drifted out by a value of Y and thereby determine a point when calibration is really needed.
BTW my ORP probe is going for about 5 months with only about 5mv of drift.

 

[Dag]

Can I get any probe to replace the one for the Aquacontroller or do I need to get it from Neptune?

 

[Henry Bowman]

Check the info on te aquacontroller but I believe most controllers in the hobby use BNC connectors. Any probe with a BNC connector will work. Pinpoint is my choice. I use their lab grade probes with good results

 

[RobbyG]

I hate unfinished threads so let me close this off.

It's exactly 4 Months since I started the Test. Yesterday I cleaned the probe and it was off by only .02
I decided to recalibrate the probe only because 4 months had passed since I did the last calibration. Through all of this time I cleaned the probe about once every 3 weeks and each time it read almost exactly right after cleaning.

My conclusion is that routine calibration seems to be overrated and that routine cleaning is what is more important. I am not telling anybody to stop calibrating their pH probe but my personal experience is that pH and ORP probes do not need calibrating very often, but should be cleaned every 3 weeks or so.