Muscadine still too acidic

[pwrose]

I have 8 gallons of muscadine aging, 1 - 5 gallon carboy and 1 - 3 gallon carboy. The 5 gallon seems to be going through MLF, in the last 2 weeks it has started bubbling again. The 3 gallon did not do this, I racked the 3 gallon this morning and it was still very acidic.
Would adding calcium carbonate now help reduce the acid or can that only be used with good results before fermentation?
I hope the 5 gallon is going through MLF and not a second ferment, It has already been back sweetened and sorbate added.

 

[Turock]

What's the PH?

 

[pwrose]

I don't hav a very accurate pH tester, bt best I can tell is somewhere between 2 and 3 closer to 3.

 

[dessertmaker]

Take a few readings with your hydrometer and make sure you're not fermenting again before you start throwing random chemicals into your carboy. If you didn't add K-Meta with your Sorbate you could easily be having a secondary fermentation.

Also, was the wine degassed already?

 

[WindyCoastWine]

I make a lot of muscadine wine and always use cold stabilization to remove the acid. Very effective and seems to really bring out a fruity flavor.

 

[pwrose]

I wasn't going to add anything to the 5 gallons until the bubbling stopped.
It was degassed a year ago, when it was already almost a year old.
For the last 6-8 months nothing has been happening to it and in the last couple of
weeks it started to bubble again.
I will be taking a SG reading later today and was planning to watch it over the next
few days to see if it is a secondary fermentation.

I have never dealt with a MLF, and really don't completely understand a MLF. I do know
what it does but as far as starting one either intentional or not I don't know how to.