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American Marine pH calibration

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mattseattle

Well-known member
Joined
Jul 15, 2003
Messages
2,694
Location
Seattle, WA
Ok, I am trying to calibrate my pH monitor. According to the instructions it says make sure the calibration fluids are room temperature. Insert probe into #7 and adjust the screw to the pH of 7.0 and do the same with #10 and adjust screw to pH of 10.0 and go back and forth adjusing if necessary. Of course rinsing the probe between moving back and forth.

My question is on the package it gives temperatures and the adjusted pH for that temperature. Do you need to actually take the temperature of each fluid and adjust your settings to that temperature/pH or just do it according to the instructions which just says 7.0 and 10.0

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Instructions:
[font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]All calibration fluids should be room temperature 68°- 86°F (20°- 30°C)[/font]
  1. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]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.[/font]
  2. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Rinse probe in room temperature tapwater.[/font]
  3. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]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.[/font]
  4. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]RECALIBRATE with #7.00 calibration fluid as step 1.[/font]
  5. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Rinse probe with fresh room temperature water.[/font]
  6. [font=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]RECALIBRATE with #4.00 (or 10.00) calibration fluid as step 3.
    [/font]
 

mattseattle

Well-known member
Joined
Jul 15, 2003
Messages
2,694
Location
Seattle, WA
ok, i tried 3 times to calibrate this thing tonight and i think my readings are incorrect.

I am using Hanna calibration fluid #7 and #10 on my American Marine pH monitor. The first time I calibrated it I got one set of readings, the 2nd time I calibrated it I got a different set and the 3rd time I got an entirely different reading. I used fresh packets on each calibration as well as fresh ro/di water to rinse the probe between packets. My tank water before calibration was 8.25. After 1st calibration it was 8.08, the 2nd time it was 8.11 and the 3rd time it was 8.15. I also checked the effluent of my calicium reactor and I had similiar differences. I didn't adjust the calcium reactor at all during the calibration so that shouldn't have changed. I can see the tank water maybe changing a tad bit but not that much. I have one more set of packets and guess I'll try the calibration again tomorrow.

Do I need to get the American Marine pH calibration fluids? I didn't think it would make a difference on what calibration fluids I used as long as they were the #7 and #10.

Any ideas?
 

NaH2O

Well-known member
Joined
Jan 25, 2004
Messages
8,568
Hmmm...Matt, I don't think the brand of calibration fluid would make a difference. I believe all pH monitors work on the same principle, so I don't think the solutions would differ in any way. As far as the temperature - do the pH calibration based on the temperature of your solution. Don't do the generalization - either take the temperature of the fluid or leave the solutions (including RO/DI to be picky) out on the counter overnight and use your room temperature.
 

gobie

dave the gobie
Joined
Dec 2, 2004
Messages
366
Location
Auburn
Hey I Had The Same Same Problem. I Couldnt Say For Sure Weather It Was The Probe Or What Ever. So I Did The Next Best Thing I Took Mine To Blue Sierria In Issaquah Than To Aquarium Paradise In Lakewood. I Learned To Put Fluids In Small Tupperware Containers And Float Them In My Sump 1 Hour Before Cal Use Shart On Back Of Fluids Anc Calibrate Accordingly
 

mattseattle

Well-known member
Joined
Jul 15, 2003
Messages
2,694
Location
Seattle, WA
well I wrote American Marine and they blamed it on the Hanna calibration fluids. They are sending me a set of their calibration fluids to see.

Right now I am guessing that my pH probe is off by .1 or a little more. I tested the effluent of my calcium reactor and the probe reported a pH of 6.4 so I checked the alkalinity. The alkalinity measured was for the 6.5 range.

I guess it could be right but my gut feeling is that it's not calibrated correctly and it's the fluid I used.

Good ideas on warming the fluid though to room temperature. I have one more set of the Hanna packets that I think I'm going to try today to see if I come up with yet another reading! :)
 
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