in my experience, the red colouring of acacia bark is not an indicator of dmt presence. the method seems fine, though i would reccomend maybe using 100ml shellite per pull. 100ml shellite generally is capable of holding roughly 1 gram of spice. acidic water soaking may work well, and will be more selective in the alkaloids it pulls than boiling, though the issue has been raised that acacia does not handle long periods of time in acidified solutions. i can attest to this with a phyllode extraction (with a very consistent species) which was accidentally taken by some friends on a camping trip (long story
)..they were gone for 2 weeks, and when i finally did the extract it was a far lower yield than the previous extractions off the same batch of leaves which were consistent at 0.3% .. the yield from 500g phyllodes was roughly 0.15%
your ph water should be between 4-5 rather than 2-3.. this is easily achievable with a smal splash of white vinegar..its also been mentioned that acacias may not handle the lower ph as well as plants like mimosa hostilis.. quite a mystery as to why this may be
it would be preferable to prepare a separate caustic solution rather than adding the dry caustic soda to the bark solution. i'd say get your acacia solution reduced down to about 500ml, and then prepare a solution of warm water, and add to that say 25g caustic soda. for reference 15g caustic soda per 150ml water will give a ph of 13. (no reason why you cant start slightly lower though and add a little more if the ph is too low).. you'll know it has been successfully basified when the solution turns black. if there is dmt present, you will see a cream coloured cloud reaction in the liquid before it turns black.. this is the dmt becoming insoluble in the acidic solution and thus falling out in its freebase form
i'd recommend freeze precipitation.. you'll know pretty quickly if your getting anything as the shellite will cloud up and you'll notice little crystals falling out. if a long time passes and still nothing, then i'd go for the evap just to see if theres anything at all in there.
hope that helps