Good idea. Everybody seems to be trying to build a better mousetrap, which I can dig. But just go over to the coco hempy thread, and read all the bitching and complaining. "I can't get my ph right". "My shit keeps drying out too fast", etc.
None of that with original Hempys, just saying.
Thats why I would never run anything in these but Hydroton. I have a minimum of ph drift and really not enough to call for adjustment when using PBP line with RO.
Seems coco would eventually mess up your pump or drippers too but I do know of a friend running 70/30 coco/hydroton with good results also on the PBP line but I believe tap.