You need to spray until you see huge amounts of male flowers on the plant. This really depends on the strain. With a 10 week strain maybe until around week 5 or 6 and there is another week to factor in cuz the plant will stop growing for at least a week when you start the treatments.
When you see the flowers starting to open up collect these male flowers, dry them and sieve them to get clean an fresh pollen.
Fertilize only a few of the lower buds and leave the rest of the plant unfertilized. I put a paper bag on the fertilized buds to keep the pollen separated and keep the rest sinsemilla. 2 days later you can remove the bags, spray these buds with fresh water to kill remaining pollen and let her do her things like always. You can yield like always and have a few small nugs full of seeds. Pretty sure this way you get at least 100-300 dark brown seeds with almost no loss in yield.
You can get colodial silver probably in each drugstore in different concentrations.
Yeah,
@Or_Gro you can also cook it down or reduce water by evaporation to get higher concentrations but its pretty cheap.
Easier to just by higher strength(50ppm's) and spray only 1-2 times the day.
BTW, these stuff was used against fungal infects back in the latest century. But I recommend to not drink too much ...
you may start to look like a blue x-men, lol!