Those small pellets of styrofoam is perilite and it's properties are nothing like styrofoam. Perilite can absorb water and let air pass through it whereas styrofoam does not.

Mineral water might be good for plants, I don't know cuz I never tried it. It might be good for an experiment down the road using a control plant and a mineral watered plant side by side. But I've always been under the impression that roots need o2.