I agree with your conclusion on the differences between what we'd call metallic particles and ions. And though both variants qualify as particles(by definition), it remains that they are inherently different in terms of composition. ie. the ion being a molecule with an extra charge removed or added, is not only volatile but also extremely small if not the smallest achievable particle size in solution. Whereas the(so called) silver Nanoparticle(or metallic) which is an elemental particle, is not only stable but also significantly larger in comparisson.

Having said that, while there is much hype and speculation on the effectiveness of each type of particle, it remains that both rely on the very same basic premise in order to function. That is to say, that it is the ion component which ultimately ends-up doing the work in the end. Though it remains that both variants have drastically different dispositions in terms of delivering the goods. And so what we end-up with in cases such as these is having to balance between stability and effectiveness. ie, The Ionic Silver solution proving to be the most effective also ends-up being the most suseptible(unstable) in terms of oxidation. Whereas the Metallic or Nanoparticle variant proves to have far more resistance and/or stability at the cost of effectiveness.
Which is something that Nanoparticle or Metallic silver marketers and sellers don't particularly like to talk about. And in other cases, will prove to be downright dishonest about by purposefully confusing terms of presenting distraction so as to avoid the implications that follow.

Whatever the case, I'd point out that while the Ionic Solutions are proving to be the most effective, that the only way to get all of the benefits from these is by propper procedure and handling; keeping it fresh, and taking it properly. ie, When the objective is to get silver ions into the bloodstream, drinking it becomes the least effective of all the intake methods. Unless of course, one is trying to treat a gastric type condition(stomach flu, food poisoning etc). Of which I'd add, there are better alternatives. And the main reasons behind this come from the inherent chemical interactions that take place between the acids in our stomachs and the silver ions. And so the best intake method for Ionic Silver is to take it sublingually rather than orally. Which is most often achieved by placing a given amount of Colloidal Silver under the tongue for a given period of time(3-5mins). Though some say longer is better. - At which point, the ions enter the bloodstream through the capillaries with little resistance.

Along these same lines, one can also make use of a Nebulizer to atomizes the Silver solution and allow it to be breathed into the lungs. Either as a treatment for lung infection and other localized conditions OR as an alternative to placing the solution under the tongue. Which btw. allows for a faster intake(ppm) as the lungs offer a much larger transdermal surface area than under the tongue.

Having said that, I'd add that the effects of the admission of silver compounds in the blood are not immediate as many would hope. ie, In my own experiences, I've discovered that it takes aprox. two to three days for the compounds to reach maximum potential using the sublingual method. Whereas Nebulization has proven to take as little as 24 hours with notable changes(or effect) as early as 4-12 hours into treatments(depending on intake frequency).

So what about Nano particle(metallic silver) then?

The short form on this appears to be where Nanoparticle silver provide greater stability and resistance against oxidation in contrast to Ionic silver. Not to be confused with the often touted black and white claims that Metallic or Elemental silver is impervious, it stands that it is also subject to oxidation, though at a much lower rate over/time. Which all works to make Nanoparticle Silver solutions far better suited for drinking and in topical applications where transdermal carriers are used(soaking etc). Though I'm not entirely sure how effective these are in sublingual applications myself as this would also require an ion exchange take place so as to enter the bloodstream. And so for me, the facts simply don't add up to the hype.

Nevertheless it remains that the Metallic Silver solutions are far more resistant to oxidation than it's Ionic counterpart. Though I'd also add that this needn't be a deal breaker as we can easily create and balance our own Ionic /Metallic solutions right in the comfort of our own homes.

So where does this leave the Homebrew Colloidal Silver maker/users?

The good news is that there is only good news for us homebrew Colloidal Silver makers. Which stands despite the attempts made by Colloidal Silver sellers to try and transform what was otherwise free and turn it into a business.

And the conclusion is that every Colloidal Silver solution ever marketed OR made, can be outperformed with Homemade solutions. ie, So far, nothing has proven to outperform the Ionic Solutions. And since ions break-down over time, sellers simply cannot maintain the potency that comes from fresh solutions. Which can be tested and proven very easily.

Likewise, Colloidal Silver sellers love to claim exclusivity when it comes to such things as their Silver solutions. When in reality, home-brewers can easily make elemental solutions also. Though the irony in all of this, is where the home-brew solutions always prove superior to the ones being sold. And it is just how this is done which becomes the best part:

When you inadvertently added Vitamin-C to your Ionic Silver solution, you effectively provided the ions with a component needed to form a stable molecule. Which in turn produced stabilized particles much like the acclaimed Nanoparticle Silver solutions. Except that here, the solution still contains ions. Which results in what we'd call an ionic/metallic solution. Or as some like to call it, A Stabilized Colloidal Silver solution. And what's more important with this, is where where we can effectively control the ion/metallic ratio in our solution to suite the task at hand.

And so, as you can see, there are many ways and methods that one can create excellent Silver solutions at home. And I for one would encourage anyone who's interested to learn how to do this themselves rather than to throw their hard earned money away at internet sellers.

Hope this helps.

PS. There are members on this forum with vested interests in the Nanoparticle (metallic) Silver market. And you'll likely find these ones participating in favor of there interests. Though in the end, you can rest assured that no one could ever take advantage of others by either encouraging or helping them into making their own Colloidal Silver at home. - and that's a fact we can all stand on.

Without allot of expensive equipment I've used and tested different brands of Colloidal Silver /ionic silver. And to what I've found is Sovereign silver to be the best of the ionic silver and goldengevity to be the best of the silver mineral. Both are what they say they are, but that being said I found ionic silver to be more effective against pathogens than silver minerals. Which is why you need such a high ppm for silver minerals to be effective. Silver ions seem to have more of a zapping effect against pathogens than silver minerals. I've done freeze tests, added salt, added vitamin c, used laser pointers, tested with ec-3 meter and put both of them in direct sunlight and next to strong magnets. The silver minerals was unaffected by the tests where silver ions changed either color or produced clumps, though that was expected and considered normal for silver ions.
Regardless of mathematics or the tyndall effect, in my logic, if the majority of the silver water molecules/compounds are larger than the wavelength of light (300 nanometers), you will see some color or hue to the silver water, if a majority of the molecules and or compounds are smaller than the wavelength of light, it will be crystal clear.
I use silver like I would an anti-biotic, only when needed, and both times I got sick, the silver mineral took much longer than silver ions to have any effect. I believe both ionic silver and silver minerals to have their place as to what ails you. From reading various things on the web, silver ions is good for colds, flu and various types of infections. Silver minerals I would use to fight cancer.
I'm not a doctor or a chemist so I cannot say this is all fact, but this has been my own experience and sifting through all of the information, disinformation out there.

Yellow with EIS means larger particles. You are mixing an acid with charged particles (ions). Your ppm went down likely because some of the ions were neutralized.