Lovász showed that a vector \(x\) defined on the arc set of a directed network \(D\) is a circulation iff for each pair of distinct vertices \(s\) and \(t\) the value of a maximum \((s,t)\)-flow in \(D\) with respect to capacities \(x\) equals the value of a maximum \((t,s)\)-flow in \(D\) with capacities \(x\) (``flow-symmetry''). In this paper, it is shown that also the more general concept of algebraic flows can be characterized by flow- symmetry. (In algebraic flows the usual addition of flow values is replaced by the composition in a commutative ordered semigroup).