Grow rocks (Hydroton or others) are used in DWC and E&F to maximize airflow to the roots. According to the chart, Hydroton traps 20% more air and 75% less water making it a far superior substrate than Growstones. Why the change?
According to Growstones:
"Perlite/Hydroton are strip mined. Growstones deliver: 3X more water saturation than Hydroton, OVER 70% more aeration than Perlite, 4X Times aeration than coco coir. "
