Splenda is counted as one carb/packet, but in the case of crystal light in the bottle, as well as other sodas and syrups sweetened with splenda, liquid splenda is used. Liquid splenda contains no carbs. The packets of splenda contain fillers used to weigh the actual splenda down since it's so concentrated. You wouldn't really have much in the packet without the fillers- the fillers are what is the actual carb. You don't really need to add carbs from the syrups and splenda sweetened drinks to your daily total, but it's still not a good idea to go overboard with the splenda sweetened drinks because 1) you're trying to wean yourself off of sweets and 2) they can be very addicting- you end up chosing the sweet drinks over water and then not meeting your daily recommended amount. I try to drink most, if not all, of my daily required water before I allow myself any sweet drinks.

Good Luck!