pH Meter

[Boofer]

What difference should the order make if the meter registers/calibrates to each of the three standards?

-Boofer-

[BigCheese]

I don't know, but the extech 110 manual says for 3 point calibration to always do 7 first and then4 and then 10.

[Boofer]

Got it. I'll try that as a possible corrective action.

I found this from linuxboy:

Not sure it's defective. Here's the process to use a pH meter with dairy products, every time at the beginning of a new batch:

- Take it out of solution cap, rinse with distilled water and wipe with a tissue paper.
- Do a 2- pt calibration, 7 and 4. Do this every time at the beginning of a make.
- Take your measurement.
- Rinse off again in water. If residue on bulb, wipe gently. Milk is thick, leaves a residue.
- Have a small container of a 7 solution, put the electrode in it, should register 7 again.
- Rinse after every use, if it looks like there's residue, wipe with tissue paper.
- never store dry

From your description, sounds like you didn't calibrate in between makes? And maybe it wasn't cleaned properly? Milk gums up reference junctions easily... it will cake on and form a barrier.

Would that resolve the difference in temps? I held the meter in the whey for several minutes. It did adjust but stopped short of where the analog meter showed.

-Boofer-

[Minamyna]

Buy the solution is kind of pricey for every make can I save the registering solution from use to use or do I have to open a new pouch each time? Seems like kind of a PITA?

What about using these? http://www.amazon.com/gp/product/B001TQQNIC/ref=pd_lpo_k2_dp_sr_1?ie=UTF8&cloe_id=24841c2b-bbc3-42cf-8fd3-aadc30249631&attrMsgId=LPWidget-A2&pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B001T77WW2&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0FVPAJB1CAS1N4P5HP8H

[JohnnyBHammerer]

You should be able to reuse your solutions.

[Minamyna]

I had been throwing it away because it comes in one time open pouches (not re-sealable bottles) and I figured the air contact would change the pH solution.

[JohnnyBHammerer]

I didn't mean to say one can't get single use solutions or that they don't go bad.  Do the pouches you have reseal?  I just ordered solutions with resealable pouches.  These are intended to be reused.  I'm waiting for the fine print that says how long after opening they expect them to last.

[JohnnyBHammerer]

My order arrived and are 'single use' packets too.  I should have purchased bottles of the solutions.  I plan to see how the buffer solutions last over time stored.

[Sailor Con Queso]

Unless they are contaminated, buffers will last indefinitely.

[Minamyna]

I would imagine putting the meter in now matter how clean it is would contaminate them?

[JohnnyBHammerer]

Because they are "buffer" solutions they are designed to hold their pH value and should resist some contamination.

[stinkycheeseandmore]

your problem MIGHT be that your PH meter is showing a temp of 92 degrees while your thermoter is showing 100. You may need to calibrate your PH meter for the proper temp.

[JohnnyBHammerer]

What difference should the order make if the meter registers/calibrates to each of the three standards?

Like Nitai said calibrate 7 then 4 or 10.  I would go as far as suggesting you calibrate 7 then 10 then check/recalibrate 7 then calibrate 4.  You want to do 4 last if you are testing for low pH and 10 last if testing for high pH values.

I don't recall seeing any temperature calibration for the Exstick.  You might check the temperature reading with a 3rd thermometer and contact ExTech if the meter is that far off.  Maybe you have a bad meter or probe.

[Boofer]

your problem MIGHT be that your PH meter is showing a temp of 92 degrees while your thermoter is showing 100. You may need to calibrate your PH meter for the proper temp.

Huh? 

The pH meter adjusts temperature reading with the level of acidity measured. I do not believe there is any adjustment for the temperature.

On my make of Esrom on Tuesday, I recalibrated my meter in this order: 7-10-4. I still had trouble seeing the pH markers I expected. I'll spell those problems out in another thread on my Esrom cheese. I think I need to give Extech Support a call. I've tried to use the meter in four makes over the past 6 weeks and I've had problems all along. I believe my cultures are in fact creating acidity but I'm just not seeing it correctly.

For those lucky souls using an Extech PH100 or PH110, how long does it usually take for you to "capture" a reading? I'm talking about the time it takes for the meter to read the pH and for you to decide that the temperature is right and the reading is good. Also, is this a case where you just put the meter in the milk and come back later to read it? Or do you hold it in there and wait for the temperature reading to settle?

-Boofer-

[wharris]

For me, its all about what you "trust".
I don't trust any one instrument.

I have 3 digital and 1 analog thermometers and two pH meters.

If I get to a mental space where I don't trust an instrument, that instrument is broken to me, and I will look to replace it.

So far, I still trust my Extech pH Meter.  All my temps are within 1-2 degrees on my digital thermometers and pH meter, and my pH readings are also very very close.

But that was not always the case.  I went through about 3 differnet meters before I started to trust my Extech pH meter.  That may change if my pH meter gets flacky, but that has not happened yet.. One never knows.

IMHO, pH is a pain. On one hand, its soooo important, and on the other hand, relying on it means trusting yout gear.  Trustworthy gear is typically not compatible with el-cheapo gear.

If you lived closer,  i would say come over and lets take a look at your pH meter...