Kephra will no doubt give more accurate figures, but I can help you with the amounts that I use.
I would first suggest that anything over 80ppm would really benefit from the use of gelatine as a capping agent.
If you increase the amount of Distilled Water, you need to increase the amount of Maltodextrin, but use the same amount of electrolyte. I use 1 ml of 0.1M Maltodextrin in 3 litres of DW, with the intention of making 20 ppm Colloidal Silver. This is not much, but it reduces the Ionic Silver Oxide beautifully and the end result is crystal clear. I find that Maltodextrin is far better than Glucose or Fructose, which both tend to result in some level of turbidity.
To make a 0.1 Molar solution of Maltodextrin, dissolve 5.05 grams of Maltodextrin powder in 100ml of distilled water. It dissolves very easily. The amount of reducing agent is not critical, so you could use a few drops of this 0.1 molar solution in a litre. Below this amount of Distilled Water (ie if you are only making 250 mls of colloidal silver) then the same few drops would be fine.