Having your salinity much over 1.026 will definitely make Xenia do that. I wouldn't expect the fish to be too troubled over it though.

This may seem like a stupid question but how would you submerge your hydrometer in the tank? Mine just floats????? So you would keep your hydrometer in the tank at all times? How come you never see hydrometers in peoples tanks????

there are ones that have suction cups (a red sea one to be exact) which just hooks on to the front of the tank.

And I guess most people use a refractometer instead of a hydrometer, it's been relegated to the "less advanced aquarist" honestly. If it didn't cost over 50 bucks, it's not a worthy measurment of anything.

i recently had to purchase a refractometer as well as i had been using my hydrometer, which was reading 1.025, but as it turns out it was out by .004 even after using the correction factors. so it was actually 1.029. no wonder my fish were stressed. all my corals had no problem though. xenia was pulsing like mad like it always does.