The term "colloidal silver" (CS) is a broad term that describes silver and/or silver salts dissolved/suspended in water. Superior forms of CS are called names like "nano-", "micro-" , "ionic" , "angstrom" , or "naked" silver and all mean virtually the same thing... A clear solution in which no salts are present containing a quite low 10+/- ppm of the smallest silver particles possible which has specific advantages over larger particle solutions.
Any vendor selling much higher ppm CS and claiming that it is superior is either ignorant or intentionally lying. Higher ppm is not better for most internal uses. Due to the laws of physics... as the ppm increases, the particles size increases (according to something called "electrical conductive bridging agglomeration".) Smaller particles can get to places (where viruses hide) that larger particles can't... including within cells and past the blood-brain barrier. Smaller particles will also exit the body more thoroughly, therefore not getting trapped in organs such as the skin which can cause argyria (remember the "blue man"?) The sweet spot for nanosilver is around 10 ppm.
Production of this nano silver requires a regulated low current (?mA) at around 18vdc, a mechanism to agitate the distilled water, and more time to make than cruder forms of CS. So unless you have the know-how and time to design the above described circuit/device... I suggest you buy one from a reputable manufacturer and follow their instructions.
I use this generator:
http://www.thesilveredge.com/gen.shtmlThe manufacturer's YT channel has instructional videos of all sorts:
https://www.youtube.com/user/stevebarwick/videosI also use this same generator to make "crude" CS consisting mostly of medium and large sized particles and likely some silver salts altogether making it slightly cloudy... the cloudier, the higher the ppm. I make the crude form only for use as an external antiseptic/hand sanitizer/surface disinfectant. The differences in production is the use of tap water (I use filtered) instead of distilled water & it takes much less time to produce than nanosilver.
Technically crude CS can be made with 1-3, 9 volt batteries in series, connected to 2 pieces of silver wire via alligator-clip jumpers... one to the "-" & one to the "+"...with silver wires submerged in a jar of water. There are endless videos demonstrating this on YT.