Okay, adding rue into the mix complicates any estimations of the amount of compounds that may precipitate out. According to my quick calculations, the amount of gelatin seems pretty good according to the info that I have on the subject tho.
When I was playing with this, I was interested in it from a point of eliminating the tannins for chromatography and not ingestion. I found that 'finning' in an alcohol solution worked much more quickly than a slightly acidic H2O solution. Freeze/thaw cycles with the acidic H2O solution worked to a degree, but simply letting the solution stand (for a couple weeks) as in wine making worked the best. Freeze/thaw worked well with alcohol.
From my notes, and talking with some people at the Ayahausca forum at the time, figure about 25% +/- tannins by weight in MHRB. (I calculated 29.3% in mine). That equals about 2.25 gm gelatin for the bark in a 9 gm sample (amount of gelatin = amount of tannins). I have no idea about rue, so the other 750 mg is probably about right? It was also suggest to use a little less gelatin for H2O solutions, so here 3 gm seems about on par again considering the addition of rue.
The precipitates should fall to the bottom, so it would seem that it is starting to work. Really, it might just be a matter of patience.
That is really about all I can offer, as I've not played with this more than a couple times. It served my purposes when I did it; removing the majority of the tannins that were interfering with reading the plates.