just thought i'd post a little help to this, since i'm planning to start consturction on mine soon. if you can't find any polymer crystals anywhere you can just go buy a pack of diapers, cut 'em open, and use the polymer crystals in there. yep, learned about that back in 7th grade science. cool huh? depending on the diapers the crystals themselves may already absorb odors, increasing this thing's potential to eliminate your growdors