I’ve heard of using rice hulls in dwc systems but I was always worried about it clogging pumps and such. I would think it would work well if you can keep it contained because it drains very well and doesn’t provide a good home for bacteria in my experience. I use it for aeration and mulch in coco coir so I’m interested to see what you find.
@Coffin_Dodger I usually dilute it about 100:1 making it about 3x the strength of hydroguard. Then I just squirt a few ml in the reservoir every time I add nutrients. The directions on the bottle I think call for using it as a foliar spray which I’ve never done.