[bradvincent]

I have a 1000 liter reef aquarium.  For those unfamiliar with this hobby, we are anal about water quality, which makes a huge difference in the health of our animals.  It is not unusual to spend hundreds of dollars a year in testing chemicals, and there is no agreement on which tests are of what importance.  Everyone agrees pH, Nitrate, Ammonia, Calcium, Alkalinity (pH change buffering potential) and density are important to keep within a certain range, although there is disagreement on whether it is important to test these and what range is optimal.

We all assume (correctly or not) that we have the correct water parameters in freshly made water (either a commercial salt mix or water straight from the ocean).  Our systems are not closed, and have many inputs (fish food, chemicals) and outputs (calcium bound in coral skeletons, waste removed with a filter called a "skimmer", etc).  Since commercial salt is expensive, seawater not always practical to get, and large water changes are stressful to aquarium inhabitants, we try to "adjust" our water back to what we consider ideal by adding chemicals rather than replacing large quantities of water.

Beyond these parameters, it is not unusual to worry about, try to test for, and write articles about: the ratio of Sodium to Chloride ions, the level of Magnesium, Potasium (as Phosphate), Boron, Carbon, Iodine, Strontium.  I am the first and only hobbyist to be concerned with Sulfur (mostly as Sulfate).  Every other major element in seawater gets attention (Bromine is mostly ignored too), roughly in order of how much of the element is present in natural seawater.  Yet the same "experts" who tell me the ratio of Sodium to Chloride ions is of vital importance will say Sulfur will always be present in levels more than are needed and is never toxic or detrimental in any quality.

I would like to measure the amount of Sulfur in my own tank, along with other large tanks that have been running a long time with minimal water changes.  If Sulfur is lower than expected, I would hypothesize it is being depleted, and experiment with adding it to improve the health of the animals.  Similarly, if it is high, I would hypothesize it is accumulating, and experiment with keeping it lower.  If it stays mostly the same, I can conclude I was wrong to worry about it, but will still sleep better at night.

What I am looking for is a relatively cheap and easy way to test how much of either Sulfur or Sulfate is present in a seawater-like solution.  Can anyone here help me?