OK, so I made a batch of colloidal silver last night. ( Remember I had mentioned a couple times that I have not had a turbid or dark batch in quite a while. ) So I tried to make a turbid sub-batch with 400 ml for the sake of the experiment. (replicating Kephra's experiment @ the start of this thread.) So I reduced most of the batch like normal but in the 400ml that was for the experiment I put 10 times the amount of reducer (diluted Karo). To my surprise that sub-batch turned out EXACTALLY like the rest of the batch. No turbidity & no darker color.
I was also planning to do the experiment Gene suggested by adding extra electrolyte to a sub-batch to see if it improved, but at that point there was no need since my entire batch of IS had plenty of electrolyte (high enough pH) to avoid any problems.
Conclusions:
1. The method I had developed over the months of just adding a tiny (stoichiometric
) amount of diluted Karo was nothing more than a "workaround" or a band aid for the real problem of pH too low (too acidic).
2. When I raised my mA (current) a number of months ago it caused me to need more electrolyte to get up into the target range. That change inadvertently solved my real problem of pH too low to allow for proper reduction with sugars (Karo, dextrose etc.) but I didn't realize it until just now.
2A. Apparently colloidal silver reduced with Cinnamon extract is nowhere near as "fussy" about pH since I have never had any problem with that. Makes sense since whatever molecule does the reduction with Cinn Extract is already there & ready to go to work by donating electrons. Whereas, with dextrose/fructose the rings have to be broken before they can donate an electron.
3. The "rule of thumb" that I was using for how much electrolyte to use is just fine when I am running at a higher current ( > 10 mA ) but when I was at lower mA it caused me to put less electrolyte resulting in a pH that was too low because I was only adding just enough electrolyte to get the current up into the target range.
4. The reason I was having inconsistent problems with turbidity was probably due to variations of the starting pH of the DW.
Other observations along the way: Months ago when I was at a lower pH I noticed that when I was reducing with Karo the color change would happen very slowly or not at all for 3 to 7 minutes of stirring (depending on temp & amount of reducer). Then all of a sudden it would go from almost clear to dark & turbid all at once ( about 15 sec. or less?) Almost like once it was pushed over the cliff then a chain reaction of some sort would happen. It's hard for me to picture what was happening on a molecular level. Conversely, now that I am at a higher pH the color change happens relatively slowly & smoothly. Not all at once.
Verification of above Conclusions: Next batch I will put in about half as much electrolyte as I am currently using to make the IS. Then I will reduce a 400 ml sub-batch with Karo. Then I will do Gene's experiment of adding back the rest of the electrolyte I left out to the rest of the big batch of IS. Then reduce 400 ml of that. Should have an interesting pic to post. I can almost guarantee it will not look like Kephra's pic in the first post of this thread.
In my mind it is well worth the time to investigate this matter since darker and more turbid colloidal silver indicates larger particle size. It is generally recognized that smaller particles are more effective at killing bacteria & viruses. So being able to make colloidal silver that is 20PPM & fully reduced that is crystal clear and is as light a color as possible is my goal.