New update with excitement: I just spent almost 2 hours cleaning my tank with a suction device that did not work, have new filter that does work, have supplies all over the place, have 2 dogs watching, plants, rocks and cave are out, air stone out, hydrometer is out, etc. I checked tank to make sure crabs were out of corner so I could put rocks then cave back in, I discover a crab is missing! I look on floor, no crab. I check under furniture, no crab. I look in sink and kitchen floor, no crab. I look in dog's mouth who likes to chase living things, no crab. I look inside containers and plants, no crab. I look under towel on floor, no crab. I check hall by front door, no crab. So, I decided to put tank back together piece by piece thinking I'll buy a new crab tomorrow. Well, good thing my lucky penny is really lucky, I found the crab inside the plastic rock cave and he would not come out. During all this my phone rings, dogs want treats, cat waits for food, etc. I held cave over water and coaxed him out by offering him the chance to watch a recorded shark week show, and he came out, was slightly scared, probably thought I would take away a priveledge of some sort. So, now everyone is fine, everything is working except the fish cleaner which I will exchange tomorrow. I would have been up all night looking for him because he would not respond even if I called him by name, that's because he doesn't have a name and wouldn't listen anyway. So, I'm going to bed soon, will study crab care and brackish water again tomorrow because I want to know how salinity changes, whether by ammonia levels, nitrates and nitrites, salt, water change, de-chlorinator, fish waste and uneaten food, etc. I still have a way to go with learning. :rolleyes