I use the floating arm hydrometer, but I do rinse it out quickly and about every third week I'll let it sit with a water/vinegar solution to remove any salt buildup. I also take my water to my lfs
where they have a refractometer. Salinity is at 1.024 and has stayed there forever.
Anyhow, I didn't have a protein skimmer, and I don't know if that has had anything to do with what's been going on but now I've bought one. It'll be here tomorrow... at least it can't hurt to have one, right?!
I've also ordered iodine, magnesium, calcium and alkalinity test kits. That way I can add what I need when I need and (hopefully) not kill anybody or anything else.
On the bright side, everybody seems to be doing great. My decorator arrow crab ate a couple big chunks of raw shrimp yesterday, my yellow watchman goby has finally moved to the front of the tank, and my fire shrimp seems to be doing great while hiding under a rock.