What to believe?

[Aquadiva]

Bought a used Pinpoint PH monitor a month or so ago. Was using it and seemed to be doing OK. Bought some Coralife PH monitor calibration fluid 7 and 10. Said probe was WAY off....oops.

OK, so I try to recalibrate and the monitor won't. Calibrate that is. So I order a new PH probe from PA, along with a packet of pinpoint calibration fluid 7 and one of 10.

Old probe will calibrate with the pinpoint calibration fluid...Hmmm...check probe with Coralife calibration fluid...both are off by more that .5

Thinking it may be the probe, I crack open the new one sent by PA. Same result....hmmm

OK, so I stick the new probe in the tank, and it reads 8.01. UGGG....so I pull out my (not so old) Red Sea ph test kit. It says 8.2....

Which one would you believe...If it is at 8.01, I need to bump it up. If it is at 8.2, I don't want to bump it that much. What should I do and why am I getting a million different readings?

TIA
Linda

 

[super cook]

Take a sample to your LFS have them do a test Im having PH problems of my own Had the same feeling also brought a Ph monitor couldnt calabrate it got different readings then I rembered Ph changes during the day my worst is 5.7 back to 8.3 would never have know if I didn't use the PH pen had to get some reef Buffer not to be Mistaken For reef builder which sent my alk way up but did not fix my Ph well I never said I was smart
sue

 

[skipp]

ph prob

I had the same exact problem and did the same as you with the same results.Stay away from the Coralife.American Marine tiped me of that the cheap fliud can be as much as + or - 2.0 off
Skipp

 

[reefer125g]

Sup
I just inst my new pin point and still have my old test kits if you would like
to stop by and bring yours we could compair the two and test your water I live
in Nashua I am trying to get a local reef meeting together for fri 19 you are more
than welcome along with friends.

 

[RobboT]

I have a few 250ml bottles of lab grade cal solution lying around. If I can find smaller clean containers and if Im coming to the Dec meeting I will bring some.