Why are my TA readings off?

TroubleShooting

Bernie Andreoli — Old Forge, Pennsylvania asks,

I crushed and sulfited my Cab grapes. In doing the initial tests I got the following readings. Brix was 23.5 (+.22 temp correction) = 23.7, S.G. 1.099 (+.013 temp correction) = 1.112, TA = .60 g/100 mL, pH = 3.02, Temp = 75 °F (24 °C) In the last WineMaker contest all the judges said my wine lacked some balance and finish. I wanted to raise the acid level to .70 g/100 mL to help with the balance and finish but I am afraid the pH will go too low and prevent the survival of the yeast. I used the Vinoferm test kit for the TA and have a digital Omega 3+ pH meter for the pH. I calibrated the meter with a 7.0 NIST buffer prior to starting the measurements (the wine shop was out of 4.01 buffer packs). I took the readings 3 times from three separately retrieved samples. I also took three samples to test the TA and besides the color change indication, I tested the samples post color change for neutral pH of which I got readings of 6.98, 7.01 and 7.13 g/L so I know I was very close. I am going to add the yeast (Premier Cuvée) so I don’t expect resolution for this dilemma prior to this year’s batch, but hope to gather info in case it happens again in the future. My thought is since I am in the TA range for a red wine, although at the low end, I am going to inoculate without any acid additions. I find this a little strange since in all the prior years I’ve had to push the acid up to get it into the range. The grapes are from St. Helena, California.