“no agricultural runoff,” Really? So what exactly is in the water that is fed to them? It’s liquid fertilizer, and it is not all absorbed, so there is “run-off.”
Simple diagram of a hydroponic system. They just pump it back through the system.
Every technical term in this article should be followed by a lengthy parenthetical explanation / definition - especially those technical terms which sound like ordinary terms and which lay readers will falsely assume they already understand.
"Agricultural run-off" can't happen in a hydroponic set-up because "agricultural run-off" is DEFINED as the UNCONTROLLED run-off of surface waters (incl. excess fertilizer and irrigation water) from LAND.
In a hydroponic set-up, everything is precisely regulated, and excess liquid RE-CAPTURED.
Regards,