Do you use temp adjusted pH calibration?

richfavinger · 12/10/2011, 06:15 PM

Was just wondering if you use temperature adjusted pH calibration? I initially calibrated my pH probe when I first got my unit (with this enabled).

I rince my pH probe in RO/DI then place in my 7.00 solution pack in a water bath along with my temperature probe so it reads the baths water temperature. I run the calibration reads something like 7.51 offset... rinse in RO/DI then I place the probe in 10.00 solution (again something like 10.52 offset)... rinse in RO/DI again, go back in 7.00 solution to check... sometimes the probe with read 0.03 to 0.05 points off... Is this normal or did I mess up?

I let the probe in each solution for about 5min. Each packet is a PinPoint 1 Use pack... I use the same solutions for the entire calibration process...

aquamanic · 12/10/2011, 06:48 PM

It's probably just your probe. If you figure your temp probe is probably only accurate to 1 degree with a tenth of a degree resolution and your pH only varies by a couple hundredths over that same 1 degree, it doesn't make much of a difference.

richfavinger · 12/10/2011, 07:14 PM

Well, I was just wondering about it reading the 0.50 something offset when calibrating. I assume it's the variation in the probe being 'corrected' out. I was use to PinPoint meters and having to zero them to 7.00 or 10.00 with the adjustment screws...

I clean and calibrate about once a month. I assume thats still OK? How much drift should I expect to see, any idea?

FYI, love the "Guide"...

aquamanic · 12/10/2011, 08:04 PM

Quote:

How much drift should I expect to see, any idea?

All probes are different I think. The less expensive BRS probes tend to drift pretty quickly. I've found my Pinpoint to be good for 2 - 3 months before recalibration. And as they age, the intervals tend to compress a bit until you just can't get good readings and have to replace them.

Charlene · 03/28/2012, 08:26 AM

The buffers for pH calibration are designed for use at 25c/77f. I run at 80 degrees so I must increase my calibration setpoints .05. Here is a handy table.

pH Temperature Correction Factors at Varying Temperatures from Standard (25°C)

Temp°C Correction Factor
40 Plus 0.45
39 Plus 0.42
38 Plus 0.39
37 Plus 0.36
36 Plus 0.33
35 Plus 0.30
34 Plus 0.27
33 Plus 0.24
32 Plus 0.21
31 Plus 0.18
30 Plus 0.15
29 Plus 0.12
28 Plus 0.09
27 Plus 0.06
26 Plus 0.03
25 0.00
24 Minus 0.03
23 Minus 0.06
22 Minus 0.09
21 Minus 0.12
20 Minus 0.15
19 Minus 0.18
18 Minus 0.21
17 Minus 0.24
16 Minus 0.27
15 Minus 0.30
14 Minus 0.33
13 Minus 0.36
12 Minus 0.39
11 Minus 0.42
10 Minus 0.45

12/10/2011, 06:15 PM	#1
richfavinger Premium Member Join Date: Aug 2004 Location: Pottstown, PA Posts: 866	Do you use temp adjusted pH calibration? Was just wondering if you use temperature adjusted pH calibration? I initially calibrated my pH probe when I first got my unit (with this enabled). I rince my pH probe in RO/DI then place in my 7.00 solution pack in a water bath along with my temperature probe so it reads the baths water temperature. I run the calibration reads something like 7.51 offset... rinse in RO/DI then I place the probe in 10.00 solution (again something like 10.52 offset)... rinse in RO/DI again, go back in 7.00 solution to check... sometimes the probe with read 0.03 to 0.05 points off... Is this normal or did I mess up? I let the probe in each solution for about 5min. Each packet is a PinPoint 1 Use pack... I use the same solutions for the entire calibration process... __________________ Rich Current Tank Info: DSA 135g (48x24x27) Starphire, Elite Aquatics M2 Sump, Reef Octopus Diablo DCS200-INT, GEO 612 Calcium Reactor + AP Carbon Doser, 2x Radion Pro Gen2, 2x VorTech MP40

12/10/2011, 06:48 PM	#2
aquamanic WHO DAT?? Join Date: Sep 2009 Location: Baton Rouge, LA Posts: 5,709	It's probably just your probe. If you figure your temp probe is probably only accurate to 1 degree with a tenth of a degree resolution and your pH only varies by a couple hundredths over that same 1 degree, it doesn't make much of a difference. __________________ I don't work for Neptune. Please put all questions into forum posts and not PM's. Visit the Neptune Community Forums for the latest Neptune updates - forum.neptunesystems.com

12/10/2011, 07:14 PM	#3
richfavinger Premium Member Join Date: Aug 2004 Location: Pottstown, PA Posts: 866	Well, I was just wondering about it reading the 0.50 something offset when calibrating. I assume it's the variation in the probe being 'corrected' out. I was use to PinPoint meters and having to zero them to 7.00 or 10.00 with the adjustment screws... I clean and calibrate about once a month. I assume thats still OK? How much drift should I expect to see, any idea? FYI, love the "Guide"... __________________ Rich Current Tank Info: DSA 135g (48x24x27) Starphire, Elite Aquatics M2 Sump, Reef Octopus Diablo DCS200-INT, GEO 612 Calcium Reactor + AP Carbon Doser, 2x Radion Pro Gen2, 2x VorTech MP40

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03/28/2012, 08:26 AM	#5
Charlene Certified Reef Fanatic Join Date: Nov 2011 Location: Peoria, il Posts: 220	The buffers for pH calibration are designed for use at 25c/77f. I run at 80 degrees so I must increase my calibration setpoints .05. Here is a handy table. pH Temperature Correction Factors at Varying Temperatures from Standard (25°C) Temp°C Correction Factor 40 Plus 0.45 39 Plus 0.42 38 Plus 0.39 37 Plus 0.36 36 Plus 0.33 35 Plus 0.30 34 Plus 0.27 33 Plus 0.24 32 Plus 0.21 31 Plus 0.18 30 Plus 0.15 29 Plus 0.12 28 Plus 0.09 27 Plus 0.06 26 Plus 0.03 25 0.00 24 Minus 0.03 23 Minus 0.06 22 Minus 0.09 21 Minus 0.12 20 Minus 0.15 19 Minus 0.18 18 Minus 0.21 17 Minus 0.24 16 Minus 0.27 15 Minus 0.30 14 Minus 0.33 13 Minus 0.36 12 Minus 0.39 11 Minus 0.42 10 Minus 0.45