I tried adding a pound of lactose sugar with the priming sugar. I couldn't tell the difference. Maybe I had too much to notice.
I heard about 3-4 people added lactose and several add splenda.
Lactose - 1 lb
Splenda - ??
Guessing two teaspoons - per 12 oz glass
If 48 bottles * 2tsp = 96 tsp
48tsp = 1 cup therefore two cups "of Splenda" would be the amount for 5 gal.