Four weeks in the barrel for the Malbec. The sour is pretty much gone. The taste is pleasant, markedly better. Definitely going another couple weeks (at least, maybe another 4 weeks since I have two gallons of unoaked Malbec to blend) in the barrel.
Initially, I was considering putting the 2019 cab-syrah through it after I got done with the super tuscan blend. But, I haven't tasted it since filtering it a couple weeks ago. If I can't save it, I'm just going to roll from the 2020 wines into the 2021s.
So was the sour taste just dissolved CO2? I have heard that the barrel makes the CO2 dissipate really fast. No first hand experience though.