Colloidal silver generator -- can't get over 20PPM

I'm generating silver using a generator with distilled water and 4-9's silver -- I can't seem to get past 18PPM. Everything I've read says you should have 40-50PPM. Anyone have experience with this?

10PPM

The most I have gotten is 17 ppm and it works just fine....

Cool, I will give that a try.

I have always used 10...They sell it in much higher Concentrates though.