Use NT Labs Pond Mature when you\'re establishing a new filter, adding new fish to a pond or at the beginning of the season to help kick start the filter after winter dormancy or medicinal treatment. Use Mature if ammonia or nitrite are above zero or after cleaning the filter. Can be used weekly to maintain a natural unfiltered pond. Use double dose at start of season or when establishing a new pond/filter. Add the required dose directly into the filter, if present. Can be used weekly to control spikes in ammonia and nitrite. Use PondLab test kits to monitor water quality. This product cannot be overdosed. Shake bottle well