salinity of test tanks

[dianelynn]

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?

[rshimek]

Originally posted by dianelynn

Hi,

Dr. Ron, Was there any difference in the salinity levels of the test tanks, or did I miss that.

They varied from about 33-37 ppt salinity.

I was wondering (newby) whether tanks maintained with higher salinity levels would experience heavier buildup of heavy metals.

There was no correlation.

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?

No, the corals would not adjust. These animals have evolved for millions of years in oceanic salinity water (35-37 ppt). They can tolerate some fluctuation, but will do very poorly outside of that range.

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?

Salinity on reefs can fluctuate +/- 3 ppt over the course of a day, depending on rainfall (lowers it), lagoonal evaporation (raises it), etc. Generally, no parameter of the reefs is unchanging. Salinity is considered "stable" in that it fluctuates around a consistent average.

I don't think we should necessarily make our tanks fluctuate, but we needn't worry too much if they do so.