I've seen it said a few times that what they brew for a serving in the amazon amounts to 30-60mg dmt from chacruna leaves. Yea, 50mg of pure dmt is a pretty sweet spot. 2.5-5g of MHRB has often been my go-to dose and I believe 1.8% would roughly be the potency of the bark I've been using.
Since you have 200 grams to work with you could start on the low end to test the waters prior to possibly upping the dose the next time. I have always brewed more than a day's worth at once and gotten to know what I have standardized in a batch. Making a large batch gives us the ability to get to know potency specifics of what we can work with for more than one single isolated session.
Good luck.
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