Question about checking TA

[three_jeeps]

I recently got a 6 gal pale of merlot juice.
I checked the SG and it was around 1.016
I checked the ph with my meter and it was about 3.6. I did not do a TA test (my NaOH bottle was empty). It would be a day or more till I could get the reagent, so I pitched the yeast and it has been about 4 days but fermentation is still going on but close to the end.

I will take another ph measurement tonight and calculate the TA.
My question is: It testing the PH at end of fermentation a good thing to do? (Most things I've read suggest it is better to test and correct before fermentation but since I did not, OK to test/correct after fermentation?)

What is the acceptable range of TA (PH?)after fermentation?

If correction is needed, what is the best way to increase TA if needed? lower TA if needed?
Thanks
J

 

[Scooter68]

Any test of of TA or pH during or immediately after fermentation is going to be considerably skewed by the CO2 presence. It's normal for the a wine must to become much more acidic at those times. So any reading you take will not be very accurate. You can take them anyway to be sure that at least temporarily the TA or pH reflects enough acid present but in reality it will skewed. Once the wine has been thoroughly degassed then the reading will be more accurate but again it's normal for a wine to end up more acidic than the original must readings.

 

[three_jeeps]

Thank you. The SG now stands at 1.000 and the ph according to my meter is 3.74.
So, my interpretation of what you stated is that I should check acidity after it has been degassed - and make any correction at that point. - correct?

I am also considering doing MLF. Since the fermentation process is done (or almost done), this would be the time to do it.

 

[Scooter68]

How long has it been since you calibrated your pH meter? Normally I would expect a wine must with an initial pH of 3.6 to drop to around 3.0-3.2 or lower during the fermentation.

 

[three_jeeps]

I always do a two point cal before I use it. I did a two point cal (using 4.01, 7.01 buffer solutions) just before I took the measurement.
I did notice a 4-5 degree F difference in what my ph meter displayed vs the digital one I have in the must. The digital in the must showed 69 degrees F, the temp on the ph meter showed 65 degrees F.
When the meter is sitting in ambient air, the temp reading is still 4-5 degrees below actual. I know that ph is corrected for temperature but I didnt think this difference would make a significant error in the ph. It may also be an indication that the ph meter is malfunctioning but I have no way to check it. It did calibrate exactly to the reference buffer ph, down to the hundreth digit.

I looked at the ph-degrees table from Hanna for the temp correction and the ph would be a bit lower, about 3.70.
On my unit, the ph probe is replacable, the temp probe is not.
Suggestions?