Life of apex pH probe?

Patto005 · Sep 29, 2015

Does anyone know what the lifespan of a standard apex pH probe is? I have calibrated mine twice, but it is still reading pH in the 7.4-7.8 range. I don't have a manual test for pH so I'm not sure if this is accurate or not

Patto005 · Oct 4, 2015

No one knows?!?!

RussM · Oct 4, 2015

Perhaps your tank water is low in pH. Since you can calibrate the probe successfully and you have nothing to compare the reading to, then there is not much reason to believe that the probe is not working. You can check it by doing a calibration, then:

rinse the probe in RO
put the probe back in the 7.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 7.0 or very close to it.
rinse the probe in RO
put the probe back in the 10.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 10.0 or very close to it.

Patto005 · Oct 5, 2015

RussM said:
Perhaps your tank water is low in pH. Since you can calibrate the probe successfully and you have nothing to compare the reading to, then there is not much reason to believe that the probe is not working. You can check it by doing a calibration, then:

rinse the probe in RO

put the probe back in the 7.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 7.0 or very close to it.

rinse the probe in RO

put the probe back in the 10.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 10.0 or very close to it

Yes I did all that, but I bought my apex used and the probe was mostly dry when I received it. I ran the calibration and it appeared to calibrate fine. But I don't know how old the probe is and I don't think my ph should be that low. I have an api freshwater ph kit, will it work fine in saltwater or will it give inaccurate readings

Patto005 · Oct 5, 2015

RussM said:
Perhaps your tank water is low in pH. Since you can calibrate the probe successfully and you have nothing to compare the reading to, then there is not much reason to believe that the probe is not working. You can check it by doing a calibration, then:

rinse the probe in RO

put the probe back in the 7.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 7.0 or very close to it.

rinse the probe in RO

put the probe back in the 10.0 calibration buffer - give it a minute or two for the reading to stabilize; it should read 10.0 or very close to it

Yes I did all that, but I bought my apex used and the probe was mostly dry when I received it. I ran the calibration and it appeared to calibrate fine. But I don't know how old the probe is and I don't think my ph should be that low. I have an api freshwater ph kit, will it work fine in saltwater or will it give inaccurate readings

Randy Holmes-Farley · Oct 5, 2015

If it read the calibration solutions OK after calibration (I'd double check that), then the probe is likely good enough. It is tells you the slope after calibration, that can be an indication of how well it is functioning, but I do not know if the Apex does that. A perfect pH probe will have a slop of 1.00 and they often drop lower over time.

Probe life varies a lot, so there's no point in giving a specific time. I've had some last for many years, and I usually accidently break them before they stop working, but mine are not among the cheaper probes available.

Randy Holmes-Farley · Oct 5, 2015

I'n not a fan of pH kits. There's no easy way to validate that they are working right.

Patto005 · Oct 6, 2015

Ok thanks a lot. I will recalibrate it and see if I get different results. So are you saying that I shouldn't use the Api freshwater kit to test it? I haven't yet because I wasn't sure if it made a difference between salt and fresh water

Randy Holmes-Farley · Oct 6, 2015

While there will be some differences in how pH dyes respond in fresh vs salt, I'm not sure any of the manufacturers actually recognize these differences and so am not sure they use their dyes differently. Fresh water pH kits, however, often do not cover the right range with appropriate precision since many freshwater tanks lie far outside the range for marine tanks.

So the answer depends on the kit and its range.