If your pellets stay dry all the time, they're not going to collect anything. However, that's not the usual state of affairs in the life of an expanded clay pellet. I've never seen roots knit into dry pellets, only wet ones.

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How not to grow dope - 'Not Your Father's Marijuana' / 'new super cannabis' / 'extra potent hydro' myths busted
DIY batwing reflector - DIY power panel to keep electrics safe and neat - DIY low-temp 3-day bud dryer - Get a harvest every 2 weeks - Photoessay: A batch of clones in rockwool - Project Big Blue Bastard: DIY 5-tube, 100 watt UV ioniser

...and don't even THINK about asking me how to hide your grow from your MOM. This is an adult sport. Give it up until you grow up.