I'm rehydrating 2 packs now and gonna pitch a 3rd pack on top of that. I'm also adding 1/2 a gal of clean water (boiled it).
Edit: fukin a.... BOTH my O2 cylinders are empty. I had to shake the carboy. I pitched 4 packs lol..... i haven't brewed a 5 gal batch in a while. 10 gal is always...