Hydrophilic stone wool (Rockwool) slabs provide an inert, pathogen-free rootzone with over 95% total pore volume. However, due to weak capillary matric suction ($\psi_m \approx -1 \text{ to } -5\text{ kPa}$), improper drainage scheduling causes rapid salt build-up (pore-water $EC > 5.5\text{ mS/cm}$) and root tip burn.
1. The Overnight Dry-Down Rule
Targeting an overnight moisture decline (dry-down) of $8\% \text{ to } 12\%$ stimulates generative flowering signals and forces air (oxygen) renewal into the slab interstitial pores before the first morning irrigation shot.
2. Interactive Substrate Optimizer
Optimize your slab moisture and drainage EC balance using our online tool: