Sorry I asked you those questions, which you answered, and then I never replied again! My bad.
I use a cheap plastic hydrometer. I just check it once every six months with a refractometer (I would do it more often, but I have yet to buy a refractometer), although it has never changed in the 8 years I've had it.
Did you have yours calibrated yet? Have you started to raise your specific gravity up?
Take a quick read through the Guides in my signature; particularly the Getting Started one, and the Parameters one. See if you can pinpoint anything on your own from there. Your calcium and magnesium are both a bit "off", but I can't see either being a real cause for concern.
I'm wondering more on your placement of the corals and what water flow you're placing them into??
On a side note...I used to lose Euphyllias all the time. I couldn't keep them alive. some would live for 12-24 hours, some would live a couple weeks. I never changed anything in my tank, but one day I added a Euphyllia that survived, and never looked back. Now I have a Euphyllia forest.