Ehsan Dashti spent a few years research and taking water samples of Reef areas around the world and there is a basic standard for what constitutes NSW.
An of coarse Randy has wrote about this
http://reefkeeping.com/issues/2005-11/rhf/
The problem with just saying a certain area is that all the corals in ones tank are not from just one area of the ocean. While Salinity can change the chemistry is change by run off from the land. We have found that if one has stable parameters and can maintain it your tank you will have success.
Oh, I'm completely aware of those standards and article which is why I pointed out we typically look for staying with in ranges of our parameters. So, if one gets into chasing numbers to constantly dose to stay in a particular tight range (Triton Set points) this can be problematic in two ways I see.
One, is the result of the test that you are trying to adjust for accurate? This can cause a lot of anxiety and confusion.
Two, trying to keep water chemistry too stable is not very natural and can cause issues when instability happens. I feel like if parameters are allowed to drift with in an acceptable range the corals can acclimate to quick changes just like they have to in nature. So, lets say when there's a power outage, or an ATO gets stuck, or an AWC gets plugged on one of the hoses, or doser stops or doesn't stop, etc. the corals are less apt to stress out as much. It seems like the long climate changes that takes decades causes more stress as coral bleaching around the world shows. But the quick seasonal to daily swings are just fine. There may be damage and some corals may not fully recover but many will.
One thing I do on my system that the Apex provides is the seasonal table. I base my entire system on that seasonal table. My temp swings seasonally, daily, and through out the day. My lights shift a little each day and increase and decrease in time and intensity seasonally. My lunar lights go on and off and adjust intensity with the moon phases. Both adjust intensity on rise, peak, and setting. The direction my pumps (maxspect gyres) run changes 4 times a day in coordination with the lunar cycle and offset by earths friction timing with the tidal bulge. They also ramp up and down in intensity during the switch in direciton. This changes in times every day.
It's all very dynamic. My corals have spawned (each at different times due to their native locations) several times now I believe due to this.
Fish love it as they get a free snack. From my Duncan.