Dr. Ron, Was there any difference in the salinity levels of the test tanks, or did I miss that. I was wondering (newby) whether tanks maintained with higher salinity levels would experience heavier buildup of heavy metals. If so, would it be possible to reduce levels over a period of time so that we did not need to add so much salt when doing changes, and would the corals adjust to living in those conditions? I have read that the reefs have a stable salinity and I have read also that they experience swings. Which is correct? If they experience swings, should our tanks do that as well?