Test strips don't measure chlorine or bromine...... They measure the oxidation potential of the water. Bromine strips then convert the "oxidation potential" reading into a bromine ppm. Chlorine strips will convert the "oxidation potential" reading into a chlorine ppm. Bromine [chlorine] test strips will register the "oxidation potential" of chlorine [bromine], but their reading (color change) wont indicate anything understandable to you (other than there's something oxidizing in your water
). The test strips are specifically calibrated to the substance they're designed to test...... by the way, chlorine/bromine test strips will also register for non-chlorine shock (MPS).