There is every indication that Pottruff is an alteration of Pottorff - both are found in Pennsylvania in the 1800s - and that the latter is itself an alteration of the German name Batdorf as shown at
http://tr.im/tg4J. Batdorf comes from a placename (Dorf means 'village') which has yet to be located as indicated at
http://www.ancestry.com/facts/batdorf-name-meaning.ashx.