Geneious Prime prompts me to remove a bad (250bp) peak? June 16, 2020 21:44 This is a known problem with the Genescan 500 ladder where this fragment does not migrate correctly. For more info see this document. Related articles Geneious Prime doesn’t recognise my ladder - how do I fix it? Getting started with microsatellites in Geneious Prime What is the gray area at the start of the traces? What is the Locus Document? Can I set the ploidy of the data?