One challenge in using the BART™ Test, Sulfate-Reducing Bacteria (SRB) is dealing with samples that naturally contain hydrogen sulfide.
Once the hydrogen sulfide concentration is above 3 mg/L, there can be a spontaneous reaction with black sulfides forming in the tester. At greater than 20 mg/L hydrogen sulfide this black iron sulfide driven reaction can be immediate.
Samples that are considered to have residual hydrogen sulfide should be pre-treated to remove this gas from the sample to prevent early false positives. The easiest manner to drive off the gas is by vigorously aerating the sample for fifteen minutes prior to starting the test. A small aquarium pump should provide adequate flows to remove the hydrogen sulfide; a small cotton plug should be placed in the air line to reduce the possibility of contamination of the sample from the air.
This information is based on Droycon, Inc Standard Methods available on their website at www.dbi.ca.