Is it basically geared towards the same type of corals? What other supplements do you add? Size of tanks that you are comparing? Fish load? Lighting difference?
I guess what I am getting at is that there are a lot of variables. The salt may be what needs to change, but it may not be.
My friend told me of his theory on different brands of salts. It kind of makes sense: he basically says "that different manufactures produce salt to go along with their specific product lines: red sea, aqua vitro, Kent, etc. People who use salinity and all the other components of their product line have great luck. When you take a tank that has been using instant ocean and BRS 2part and throw salinity or the red sea coral pro into the mix, you might be asking for trouble.
A lot of the high end salts are made to be used with that same brands product line. Mix and matching can lead to ionic imbalances."
Interesting theory.