Potassium sorbate does NOT stop an active fermentation, nor does potassium metabisulphite. The wine MUST be still before it can be stabilized.
Once you're positive the fermentation is stopped, add sorbate and kmeta according to package directions. If the wine is active, you might get lucky and get a slightly fizzy wine (had this happen) or you might start blowing corks (had this happen, too!).
Some recommend waiting a day or two before sweetening. However, most kits with an F-pack do it all at once, so I believe waiting is not necessary. That said, if you feel better waiting -- then wait. It won't hurt anything.
Good advice has been posted regarding how to sweeten. The hydrometer idea is probably the most scientific and "put in less than you think you need" is top notch!
Once you're positive the fermentation is stopped, add sorbate and kmeta according to package directions. If the wine is active, you might get lucky and get a slightly fizzy wine (had this happen) or you might start blowing corks (had this happen, too!).
Some recommend waiting a day or two before sweetening. However, most kits with an F-pack do it all at once, so I believe waiting is not necessary. That said, if you feel better waiting -- then wait. It won't hurt anything.
Good advice has been posted regarding how to sweeten. The hydrometer idea is probably the most scientific and "put in less than you think you need" is top notch!