I've heard talk of citrus, cinnamon, amaretto and potentially other flavours causing plastic tanks to crack. It's just not worth it! Considering there's no way to know what goes into some complex blends, it just seems pointless to bother with plastic. The only plastic tanks I ever bought were a few cheap EVOD-style throwaways to let my dad sample my juice collection in an effort to convert him from his tobacco habit. Haven't found a use for them since.