Redox indicators were employed to monitor redox status in a bioaugmented, sediment-packed column during the dechlorination of tetrachloroethene (PCE) to ethene (ETH). The speciation of the indicators thionine and cresyl violet, immobilized on transparent films, was spectrometrically monitored with a flow sensor based on circulating the column solution through a specially constructed flow cell placed in a conventional spectrometer. A fiber optic redox probe based on immobilized azure C was constructed. A 75-cm column with 4 sets of ports along the column axis at regular intervals was constructed and packed with aquifer material. These ports enabled sampling to determine concentrations of chlorinated ethene species and allowed for in situ or non-invasive monitoring of redox conditions with negligible O₂ contamination. The flow sensor and fiber optic sensor showed similar responses to redox conditions in the column. After 60 days, complete conversion of PCE to ETH occurred by the end of the column and the redox level indicated by the indicators was consistent throughout the column. Significant formation of vinyl chloride or ETH was observed only after significant reduction of cresyl violet.