Ph calibration

[scotty333]

Guys
I didn’t notice the temperature of rodi needs to be 30 degrees when calibrating my ph probe
The water was more like 15 degrees , I did the 9.18 but not the 6 and 4

I guess it won’t be accurate now?

 

[Randy Holmes-Farley]

Ro/di is being used how?

 

[scotty333]

From my ro unit

 

[fishyjoes]

Calibrating a PH probe doesn't normally involve RO/DI water, just the calibration solutions. So the question is what are you doing with RO water?

I calibrate using 7.0 and 10.0 calibration solutions, no RO at all.
The solutions I use (pinpoint brand) come with a temperature correction chart.
For example, at 30C the 10.0 solution I use corrects to 9.965 and reads 10.0 at 25C

 

[Garf]

Calibrating a PH probe doesn't normally involve RO/DI water, just the calibration solutions. So the question is what are you doing with RO water?

I calibrate using 7.0 and 10.0 calibration solutions, no RO at all.
The solutions I use (pinpoint brand) come with a temperature correction chart.
For example, at 30C the 10.0 solution I use corrects to 9.965 and reads 10.0 at 25C

I'm thinking the pH 9.18 is borax, therefore mixing with RO water to make the calibration solution. I've never seen dry pH 6 and 4 powders however.

 

[Randy Holmes-Farley]

From my ro unit

But for what purpose? Mixed with what?

 

[scotty333]

Yeah 4.01 , 6.86 and 9.18 dry powder mixed with 250ml water , has a chart with the different temperatures will be different ph . When I did the 4 and 6 I never saw the chart but the probe read core the solution

 

[scotty333]

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www.joom.com

 

[Garf]

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www.joom.com

It sais 25C on those packets. I would just do the pH6.86 one again, you don't need to calibrate to pH 4 if the probe is going to measure the water in a reef tank and not a calcium reactor, that will confuse everything. Depending on if you have to adjust anything, another pH9.18 check may be wise.

 

[scotty333]

Ordered the powders , will recalibrate it when they arrive

 

[Malcontent]

If the probe/meter have automatic temperature calibration then it shouldn't matter, right?

 

[scotty333]

Right, I don’t know about that
Would it read differently if at another temperature?

 

[Randy Holmes-Farley]

Some pH buffers will vary in their pH with temp in ways and for reasons that the meter cannot correct for. Good buffered will include such information. If not, and you know what the buffer is, you can likely look them up.

 

[scotty333]

Cheers boss