Lowe's has food safe/BPA free 5 gal buckets (for $4) - anyone used these as a secondary? Seems like they would work perfectly and would allow little headspace like a carboy. All I need to buy is a lid & an airlock from my LHBS. Esp. good for my setup as my ferm freezer (which is large enough for two buckets) has a shelf that doesn't allow me to use my 6.5gal bucket with the airlock.