That is likely your #1 issue.
That hydrometer is notorious for being waaaaay off.
I used one when i first started and my ran my reef @ 1.031 for years unknowingly.
Get yourself one of these ASAP. Its more accurate than anything else youll use.
Ensure that your equipment is reading correctly and your aquarium is at the right salinity with Tropic Marin's High Precision Hydrometer. Many tank inhabitants are sensitive even to minor changes of the water conditions. Unfortunately as we've all experienced, salinity reading equipment as...
www.bulkreefsupply.com
After you get it and dial your salinity in, tackle your alk, calcium and magnesium levels.
What salt are you using?