I would go with Dean's calculator amount.
There was an old post (now removed) that suggested that ~1tsp/liter for 320ppm should be sufficient. I used that for a long time, but I found that I was getting silver oxide coming out of the solution. I was using distilled water jugs for storage, and I noticed that if I kept ionic silver in one, the jug would discolor with the grey silver oxide. When I kept my 20ppm diluted gelatin capped maltodextrin reduced colloidal silver in a distilled water jug, it also got the silver oxide on the sides.
When Dean published his calculator (tyvm!), a liter of 320ppm calls for 4,275mg maltodextrin, which is about 2tsps, or twice what I was using. Now if I store my diluted 20ppm in a distilled water jug, it no longer discolors the jug with silver oxide. What that's telling me is that I was not initially using enough maltodextrin to fully reduce my colloidal silver.
Yes, it definitely has a taste (I'm glad to hear others get the same), but it is also fully reduced. The taste is more noticeable when I use 320ppm straight for brushing my teeth, but much less so diluted to 20ppm for drinking. I always figured the sodium carbonate may be lending itself to the taste too.