Automatics go into flower way too fast for colloidal silver to work consistently. The silver does not technically cause male flowers. Technically, the silver PREVENTS female flowers by blocking ethylene. Then, the plant will do the only other thing it can do...make pollen sacks.
On a regular plant, you start spraying colloidal silver about a week before you switch to 12/12 for flowering, and then you keep spraying until you see pollen sacks halfway formed. This totally prevents female flowers from forming.
Autos go straight into flowering from seedling. You need something stronger. You need Silver Thiosulfate, otherwise known as STS.
PEACE