So disregard the question I just asked on your thread
I'm doing 2 coco/1 dirt. Measuring instruments are whatever's handy. It's my understanding that coco lowers the perched water table because of it's larger particle size (as opposed to say, dirt). A wick out the hempy hole may, or may not lower the table... but I'm not sure that means a tinker's dam in a hempy.
I added the dirt because I have a thing about smells. Nice wines, creosotey scotch, cucumber/rose infused gin, sniffing my fingers after I bust up a bud, stuff like that
And more practically, because of it's Ph buffering, and my crappy water.
I am liking the idea of the lava rocks more and more. The perlite I have can go in the veggie garden... that's where all the dumpings are going anyway.