Hellolights and chanpionlighting are both good places to check for light fixtures.
Salinity varies slightly from place to place around the world, and also varies somewhat with the seasons (affected by temperature and precipitation). The average ocean salinity is 35 pt. This number varies between about 32 and 37 pt. Rainfall, evaporation, river runoff, and ice formation cause the variations.
Warm temperatures and high evaporation rates (particularly in shallow seas), raise the salinity. Warmer waters will tend to have higher salinity than cooler waters. Therefore you would expect Catalina water to have a lower SG
than a tropical reef. Commercial salt mixes are formulated to be mixed to NSW
levels of the average tropical reef.