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Probe Calibration

1369 Views 9 Replies 6 Participants Last post by  crazy loaches
I am getting the Milwaukee SMS122. Is the calibration fluid a once and done, or can it be saved for periodic calibration?

Also, over threads have indicated that the probe can be fully submerged in the tank. Is this correct; has anyone encountered a problem installing it like that?
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I have an SMS122, and bought a boxful of the calibration packets with it. Waste of money, I only used like two or three of them.

Now I just do a chemical pH test with my API test kit and adjust the SMS122 to match. I get very little drift in the meter.

I have my probe submerged about 1.5" - 2". Never tried submerging it all the way.

Regards,
Mike
Thanks. I see that in Pinpoint's instructions it actually says you can submerge it completely. Any idea why on those you need to calibrate the slope and on the Milwaukee you do not?
Argh - you're making my head hurt - :) - it's been awhile since I researched this.

The SMS122 does have a slope adjustment screw on the back, but as I recall, the recommendation was to leave it alone. I've never touched mine.

Mike
I saw the recommendations to only calibrate 7.0, but nobody seemed to know why.

Does the probe float or does it sink?
I have an SMS too. It has been fully emerged for 3 years and calibrated twice.
fish tank water is generally in the 6-8pH range so we only calibrate to 7
since calibrating to 4 or 10 is pointless as we never get near that reading.

probes will generally sink unless specifically designed and marketed to float.
most people use a suction cup to hold them in place against the tank glass.
I am getting the Milwaukee SMS122. Is the calibration fluid a once and done, or can it be saved for periodic calibration?
The calibration fluid is a one time use when you use the small packets.

I have two of these SMS 122 controllers. I buy the bigger 7.01 solution bottles so that I can use some in a pill bottle and store the rest.

When I calibrate them, I do several things:
I clean them with a tooth brush with aquarium water plus I have an electrode cleaner solution to soak them in.

I rinse them in Deionized water.

Then I soak them in a pill bottle container with some of the 7.01 pH buffer solution.

After a few minutes, I remove each one and I soak each them in a clean separate bath of the 7.01 buffer and I adjust them as needed. They may be usually 0.1 to 0.2 pH units off sometimes. Many times, it's still reading right correctly.

Always use a new buffer solution for each test except for the initial 7.01 solution soaking. Use a new solution for the calibration.


Also, over threads have indicated that the probe can be fully submerged in the tank. Is this correct; has anyone encountered a problem installing it like that?
I don't. I keep the black top above the water line.

I use a 1/2" PVC Box adapter by Carlon that I get at Lowe's. It fits into an aquarium heater holder @ $0.42 each. On the top of it, it says:
Carlon 1/2" EDD6D PVC
http://www.carlon.com/sd-cgi/hsrun....PRODUCTWINDOW.run?ProductNameFromSearch=E996D

These probe holders may work OK well too:
http://www.marinedepot.com/ps_ViewItem~idProduct~AL3111~tab~1.html

There are several pH probe holders on the market that may work well for you.

I hope that this helps you, Zelmo.

Good Luck!:eek:
Left C
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Thanks for all of the tips and insights. I got the unit yesterday and didn't get it installed because it took too long to find mounting screws small enough to fit through the slots.

Anyway, the instructions say not be concerned about a salt type buildup around the protective cap. Well, it is completely encrusted. I am assuming I want to clean this up, but how hard is that going to be? If I dunk it in a container of tank water will that do it, or do I need to be more aggressive?

Finally, what about placement in the tank? This will be in a 150g tank with the CO2 supplied via a reactor in the return of a 2028 at one end of the tank, and a Fluval 403 at the other end. I have the return bars mounted vertically so that the one supplying the CO2 shoots across the back wall, and the other angles out 45 degrees creating a swirling effect. If I put it between the two will I get a bad reading because of being too close to the source of CO2?

Edited:

Well, a trip to the Pinpoint website and instructions answered the question about cleaning up the probe. It would be nice if Milwaukee's instrucutions were better.

What about placement in the tank? I intend to test several locations to see if there is any deviation, but it would be nice to know ahead of time what to expect.
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fish tank water is generally in the 6-8pH range so we only calibrate to 7
since calibrating to 4 or 10 is pointless as we never get near that reading.

probes will generally sink unless specifically designed and marketed to float.
most people use a suction cup to hold them in place against the tank glass.

While a two point calibration may not be critical I would not endorse your method of thinking. For one thing, many planted tanks run pH midway between 4 than 7, if not closer to 4, and some I've even seen in the 3's (especially for breeding). I know on my controller when you callibrate it I dont even think you can do it without 2 points since it first asks for the high solution then the low one automatically. And if your using a controller why not get it as accurate as you can? If your not seeking precision than why bother with a controller?
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