Kief,
Don't know how much was in the packets you added but if they were close to what Winexpert adds to their kits the sorbate packet would contain 5.5 grams.
Based on the numbers I could find you want to add 1/2 tsp per gallon of sorbate to prevent refermentation. Sorbate weighs ~1.25 grams per 1/2 tsp so the total amount you need is 1.5 tsp or 3.75 grams. One half of the package if is was 5.5 grams would have been 2.75 grams if you did it perfectly.
Obviously it wasn't enough sorbate due to your refermentation so I guess you have no choice and wait until it stops and try again.
Just for clarification on the amount of sorbate that isincluded in Winexpert kits. It is 5.5 grams and this amount is calculated toyield just under 200 PPM, a rate consistent with preventing bacterial growth, while staying below the taste threshold of 99.9% of the population.
WE kits that have an F-Pack for sweeting actually add more sorbate than the 5.5 grams since the F-Pack does contains additional sorbate.
Hope this makes sense and bottom line is that when adding chemicals you need to follow the instructions for that particular brand since they are not all interchangeable.
