well in the very near future im getting a 55g . i wanted to know the equipment reuired to properly maintain the tank. substrate will definately be sand.would an aquaclear 500 bee ok?also i know i have to keep a very close eye on the salinity level.what instrument is required to ckeck the levels?i heard of a hygrometer and other stuff but im new to brackish tanks. im not in a hurry to get it all i just want to be sur i can prperly care for my fish. im already well informed bout the fish im getting so now i just want to get the specifics . could someone please enumerate the equipment required. i know i need marine mix salt but im having a hard time finding info on the equipment.