An error-corrector for pyrosequenced amplicon reads. Acacia reduces the number and complexity of alignments. Rather than performing all-against-all alignments in a cluster, each read in the cluster is aligned to a dynamically updated cluster consensus; the alignment algorithm is made more efficient using heuristics that only consider homopolymer over and under-calls. Acacia uses a quicker but less sensitive statistical approach to distinguish between error and genuine sequence differences. Acacia is an alternative to AmpliconNoise and Denoiser that maintains sensitivity without compromising genuine signal in the data.