Re: diluting 500 ppm silver?

Yes, DMPS appears to have a good safety record and it certainly is much preferable to the side-effect prone BAPS.

Now, the company you list states:

"Ultra Silver is proven to have a mean particle size of 35.2 nanometers"

Which means that there are both larger (perhaps much larger) and smaller particles which average out to 35.2 nanometers in size.  I am personally not comfortable with the product and it's high concentration and since the smallest PPM product they sell is 1000 PPM, I would rather imagine that any further dilution will simply give you a lot of large particle silver with diminuishing effectiveness the further you dilute it.

I also note that they really do not state definitively whether or not they use protein to help keep their particles in suspension, but I do not see how they could keep from doing so, given the large size of at least some of their particles and the fact that silver particles begin to agglomerate (lump together) at concentrations of greater than 20 PPM, and do so increasingly as the PPM count rises.

All the best,

Tony