[tang daddy]

Could be the refractometer, I use 2 refractometer on my tank to test water, if one looks off I use the other one. Did you accidently drop your refractometer?
That could cause the discreptancy. Try adding salt water to your system instead of top off water to raise it slowly. Your colonies are probably under lots of stress so you don't want to shock them even more. How are the other corals and fish doing?

What salt are you using?

I also keep my salinity at 1.026 as this gives me a buffer of .02 either way which is always what my refractometer ago off on but usually 2 points higher so if it reads 1.026 it's sometimes 1.024. Don't thing I've ever heard a refractometer being that far off. Also measuring water when it's warm can give you a different reading than room temp but not by much.