Effect of high Salinity

[vic622]

I was just about to do my weekly cleaning and was testing my replacement water & tank water to make sure they were close/same and my tank is showing 1.030 using a Coralife Deep Six Hydrometer.

I'll lower the salinity to 1.025-1.027, but I was wondering if there are any specific negative side effects to having a high salinity?

I know that other elements can be toxic, but what about NaCl?
How high before there are toxic effects?

Vic