In my experience high PPM Colloidal Silver just doesn't work very well. Not believing myself I've bought high PPM CS several times only to have zero results.
On one occasion I had a tooth infection and bought the 500PPM stuff (cost $90) at a healthfood store to try to knock it out right away. After swishing the stuff around in my mouth repeatedly for about an hour not even slight relief. Fortunately they returned it and I tried some basic 10ppm sovereign silver that did the trick almost immediately.
Even more strange but at this point undeniable is that home made silver tends to work better than commercial for most uses. I've bought MesoSilver, gallons of Utopia-Silver , and the stuff from my SilverGen maker simply works better. Whether for direct application, colds, flues, vaporizing, etc.
I even have a relatively large sample of people I've tried it on. From instructors to students at the vocational school I own, they're amazed at how well the stuff works. I can't tell you how many instructors, receptionists, students etc have been able to stay in school for the day instead of leaving thanks to my homemade CS. And I have to tell you as health plans go you couldn't possibly find a cheaper one than all the free home made Colloidal Silver you need - when you need it. ;)