[justinl]

Okay Im setting up my 60gal acrylic mantis shrimp tank but Im pretty much broke (yay for university student life). The only thing I need now is rubble. I know I can use shells and rubble of dead or live rock, but can I just use rocks/pebbles I'd find on the ground (ie free!)? Should I worry about bad stuff like toxins/silicates getting in my tank?

I apologize if this is a noob question.