Rockwool cubes on a mat covered by panda film. You could grow in hydroton in full skirt pots sitting on a rockwool mat or coco mat covered by panda film and would cut down on salt buildup but you would need a much larger reservoir to flood properly without the xtra hydroton. Would be easier to set up a top drip though. So many options with hydroponics. I think once you get your ph dialed in and cover the hydroton you’ll be ok. I would look into the flood cycles and maybe talk to someone who has done full tables of hydroton because I think it would be better to flood more often than not so the hydroton doesn’t dry out and cause as much salt buildup. Also could look into other nutrients that doesn’t leave as much salt behind, GH is one of the worst for salt buildup.
On the panda film a lot of box stores like Lowe’s and Home Depot carry it along with eBay and most grow shops. A google search should do it. It’s just a roll of plastic with black and white sides. Hope this helps.
