Your tank's coming along nicely and looks great!~
Like a couple have already said, it is a wise investment to get yourself a refractometer. You would be surprised how different your SG readings will be compared to the hydrometer. ex. I had the Red Sea hydrometer and it tested my SG at 1.026. When I tested it with the refractometer, it was actually 1.030! The refractometer will give you accurate readings. For test kits, I use the API Saltwater Master kit and the API Reef Master test kit. It makes it a lot easier checking your own water when you sense that something is "off" instead of having to take your water to the LFS where they will usually say "everything looks good!". Your corals will sometimes give you an indication of something being "off" with your water. Gsp may not open up, mushrooms may shrivel, etc.. When I first started in the hobby, I was obsessed with checking my parameters and checked all parameters when I came in to work and checked them again before I left work. Now, I just check it once a week and when/if anything looks "off". Once your tank has been set up for awhile, you will find that your parameters remain stable and you don't have to check for "everything" all the time.
As for more clean up crew suggestions, you should get a conch. You will be amazed by what an awesome job they do at helping keep the sandbed clean. They literally look like they are vacuuming your sandbed. Also, some astrea snails will be good too.
Looking good, though!~