I found the article I was looking for which discusses salinity and how to measure it by Randy Holmes Farley... http://reefkeeping.com/issues/2004-06/rhf/index.php . I only include it because your salinity seems so low that I question if it is an accurate reading. The begining discusses salinity and the end the different ways to measure it.

When keeping stoney corals I would recommend an SG no lower that 1.024 and keep in mind natural sea water is about 7 DKH & ca is close to 400. Unless running zeo I suggest keeping the alk closer to 8-9 DHK and ca 420-440. Your fish will be fine & your corals will be happy.