I would keep salinity at 1.024-1.026. That would be 32ppt-35ppt. When the salinity reading is too high, just siphon out and add fresh water until you get the desired reading. Remember, water evaporates and salt does not, so when your water level goes down due to evaporation , your salinity level will rise. Just top off with fresh water to lower the salt content. A refractometer is more accurate to measure salt content. A hydrometer can be close enough for a fish only tank but if you're planning a reef tank, you definitely need the refractometer. After you feel the hydrometer with water, you need to bounce it on the counter top a couple of times and then let the needle settle. You need to do this because air bubbles on the hydrometer needle can throw off the salinity reading. I haven't read any previous answers to your post, so I'm probably already duplicating what someone has already told you. Crushed coral is sort of messy when you first put it in the tank. It's a good choice though because it'll help buffer your pH level. Good luck. I'll be glad to help you whenever you need it. Just let me know.
