Yes, straight perlite.
You use solid buckets with a hole drilled in the side 5cm up from the bottom.
Following the advice of
@bluter I trickle some water down into the perlite at the base of the side every day until the roots reach the res at the bottom of the bucket.
Then I fertigate every 3rd day in early veg. One reason I'm using transparent containers right now is to make it easier to tell when I need to up the frequency, going first to every other day, and then every day.
You have to make sure to get plenty of runoff to clear older nutrients out of the res.
I'd suggest reading the journals of
@bluter @Braddah Waiheesohai and
@FelipeBlu as I learned a lot from them, and you might find
Hempy Headquarters interesting as well.