Yes, would you please contact them and let us know what happens to the sulfur? There are sulfur-fixing bacteria which convert sulfur to hydrogen sulfide gas, but I thought they were anaerobic. Wish I knew more about this.
you are correct. I am a wastewater treatment plant operator so we are trained in Hydrogen Sulphide.
the bacteria reduce sulphur compounds to form hydrogen sulphide gas. they are indeed anaerobic.
the only place where these bacteria are going to live in aquaria would be in saltwater 'plenum's or deep sand beds where nitrate reducing bacteria also will exist in anoxic/anaerobic zones - giving off nitrogen gas in the process.
there really aren't anoxic zones in most freshwater setups - its possible in some setups with sand bottoms that are not turned over often though. but these days, its pretty rare - most people are pretty good about avoiding 'dead pockets' in sand..