Hi there,
as i am preparing another rue extraction (A/B), i was wondering if it is really necessary to grind the seeds down to a powder which also means a lot of filtering work to do.

So i wanted to ask if there's some experiences about this, especially regarding yields.

Thanks for your answers in forehand and hopefully this will help a few people ease their extractions...

Have a nice day!

No, it's not necessary and just makes the filtering harder (it's still hard anyway because of micro-particulates). Just make sure to boil at least 3 times. My yields are always between 2-3% very pure harmalas.

I filter through a T-shirt first to remove the seeds after each boil, then squeeze to remove all liquid. This crude liquid is still really dirty, so I would let it sit for at least a day after the crude filtering to let the particles settle, then slowly pour off the mostly-clean liquid. If you don't do this, it will take many times longer to filter and your life will be hard. Only then do I use a coffee filter, and then run it through clean filters repeatedly until I can filter a liter in <5 minutes, this is a better metric to know when you're done filtering than visual appearance.

Also, I would do a Manske precipitation with salt before basing your alkaloids. If you do the basing before the manske, many dark brown unwanted particles will precipitate out and make it really hard to get your freebase alkaloids.

The most efficient procedure to get pure harmalas in my experience is:
boil 3x -> crude filter -> settle for 24 hours -> fine filter many times -> manske -> redissolve solids in water -> filter many times again -> base alkaloids -> collect -> redissolve solids in acidic water -> filter again -> manske again.

This should produce nice crystals with the least effort, provided that you make sure to filter as much as possible. When you think you're done filtering, filter three more times. There are some really small particles that can make it through the coffee filter and show up as a brown stain on the filter. Filter until the filter is only yellow (no brown at all).