PH Probe calibration

[sailfintang]

Recently I obtained a pinoint ph monitor and had purchased anew probe from BRS. I also purchased the pinpoint 7 and 10 calibration fluids. I was following the instructions from pinppoints sight for calibration

1) With monitor turned "ON", place the end of the pH probe into
calibration fluid #7.00 Using a miniature screwdriver, turn screw
labeled #7 on the front panel of the meter (see diagram) until display
reaches 7.00 exactly.
2) Rinse probe in room temperature tapwater.
3) Place pH probe into calibration fluid #4.00 (or #10.00). Wait several
seconds for reading to stabilize. If adjustment is necessary, turn screw
labeled 4, 10 on the front panel of the meter (see diagram) until the
reading reaches 4.00 (or 10.00) exactly.
4) RECALIBRATE with #7.00 calibration fluid as step 1.
5) Rinse probe with fresh room temperature water.
6) RECALIBRATE with #4.00 (or 10.00) calibration fluid as step 3.
Continue the calibration between both fluids. The two-point calibration is
fully complete when monitor will display both calibration fluids correctly
without any adjustment necessary.

But to my surprise I could only get the monitor to calibrate to the 7 solution and not the 10. I would only go to about 9.2x even when adjusting the calibration knobs. So now even if used in my tank I receive a false reading. Any one else ever have any issues calibrating their probes. This is my first time around the block with this I figured it would be a 5 minutes process but it is getting me pretty angry. Already tried recalibrating the probe too and no luck with that. Any ideas, help or suggestions would be appreciated?

 

[GTriever]

The first time I did it, it took a bit longer than 5 minutes, but at least it did calibrate. I noticed that it's hard to get the screwdriver lined up sometimes on the screw slot and you think you're turning a knob when you're not. But -- only to 9.2 at full range when adjusting the 4/10 screw? And with a new probe? Sort of leads me to think low battery or bad meter. Or, probe incompatibility. What do you mean "tried recalibrating the probe too"? What is the model number of the probe, because my probe has no adjustments.

 

[sailfintang]

<a href=showthread.php?s=&postid=15463292#post15463292 target=_blank>Originally posted</a> by GTriever
The first time I did it, it took a bit longer than 5 minutes, but at least it did calibrate. I noticed that it's hard to get the screwdriver lined up sometimes on the screw slot and you think you're turning a knob when you're not. But -- only to 9.2 at full range when adjusting the 4/10 screw? And with a new probe? Sort of leads me to think low battery or bad meter. Or, probe incompatibility. What do you mean "tried recalibrating the probe too"? What is the model number of the probe, because my probe has no adjustments.

Probe is standard one from Bulk Reef Supply.

By recalibrate I tried two new solution packets 7 and 10 to get the probe to read correctly thinking maybe I had a bad calibration packet, but the same thing happened using the new solution only went to around 9 so in my display my ph meter is off by about 1.00 reading. There is no battery in my meter it connects via wall outlet/adapter.

 

[GTriever]

Is the probe the Pinpoint brand or BRS's house brand generic probe? If it's BRS's and it's a new probe, you might try to exchange it for another one on the odd chance that it's bad. Sorry, but I've never used anything besides the Pinpoint probes myself.


In the meantime, let's try a couple of things here:

(1) Get a fresh 9V battery and install it in the meter. Sometimes the AC adapter can pick up interference and it can affect the readings.

(2) Turn both screws to the extreme length of adjustment, either clockwise or counter-clockwise, it doesn't matter. Now, for EACH adjuster, count the number of complete turns it takes you to turn it all the way to the other end of the range. After doing that, preset both by turning the adjusting screws in the opposite direction to 1/2 the number of turns you just counted.

(3) Try recalibrating the meter, with the 7 adjustment being first.

Be sure to rinse the probe very well before putting it in the 10 solution so you don't contaminate the 10 solution with the 7. I usually allow about 30 seconds to 1 minute for the meter to stabilize before trying to adjust between solutions. Do the same thing when moving back and forth between the adjustments, rinse very well and give it plenty of time to stabilize. If after this it still won't adjust, then a call either to BRS for a new probe or to Pinpoint for meter repairs is probably necessary.

Good Luck!

 

[sailfintang]

Thanks will try these tests later tonight.

 

[GlassReef]

Sounds like a bad meter to me. If you haven't already, give Ryan or Andrew a call at BRS. They'll do whatever's necessary to get your situation straightened out, and might be able to diagnose the problem over the phone. Great people!

 

[sailfintang]

If its a bad meter what wil BRS be able to do, if it is a bad probe then they may help me out. I wil ltry and check it tonight.