Would the malolactic fermentation be that which anir dendroica was speaking about earlier with the reduction of tartness? That is, if it finishes fermenting and it tastes a little sour still, I should let it keep doing its thing. If it finishes fermenting and the tartness / sweet / dry level is to my liking, it could benefit from halting any more malolactic fermentation with the addition of sulphites?
Lastly I have another question for you folks if you care to chime in again. Since my apples are quite tart, does this indicate that they could produce a must which is too acidic to ferment?