Complex sentence: Note that all single malts are also purely from a pot still, but are generally distilled twice, whereas the whiskeys used for pure pot still whiskeys are generally distilled three times and use partially unmalted barley so they cannot be technically called a single malt.
Split into simpler sentences: Note that all single malts are also purely from a pot still, but are generally distilled twice, whereas the whiskeys used for pure pot still whiskeys are generally distilled three times. Pure pot still whiskeys use partially unmalted barley so they cannot be technically called a single malt.