r/o

I am new to the forum and not sure if I'm in the right department. Even though this is not my first tank I often still feel like a beginner b/c I'm always learning something new. Specs: 55 G, started up Dec. 2017 5 fish: 1 neon dwarf gourami, 1 emerald cory, 1 zebra danio, 2 platies Temp: 76...