The more I read on the deck forum, the more confused I get about decking materials. We want to redo an aging second story deck, which is situated over a lower level patio and small fish pond. My husband and I are retired and want to build something that will require a minimum of maintenance since this is our retirement home. We were thinking of Weyerhaeuser ChoiceDek or another composite product, but I've seen concerns posted about mold issues. We're also concerned about products we would need to clean and seal the deck, since there is a fish pond below it,and we don't want to introduce chemicals into the pond. We'd also like to install some kind of an underdeck so that we can use the patio without water and/or dirt filtering down - such an underdeck on the second story deck would also allow us to leave our patio furniture and cushions out at night. Given these issues, if it were you, what kind of deck material would you choose.