if you use live rock and live sand you should be able to add your cleanup crew, snails and hermit crabs in two weeks. Another week and go with fish, something like a tank-raised clownfish. 3-6 months you could add hardy coral if you have enough lighting. If you just want fish and live rock(FOWLR) you can use normal lighting.
well i just bought instant ocean sea salt for 50 u.s. gallons and also a hydrometer. i have an internal filter with bio media and sponge which is good for a 55 gal. will that be a good filter? Also, should i use all the sea salt since i ave a 40 gallon and its enough for 50?
Oh yeah, make sure you get the right light for whatever you decide you are going to keep. I'm on the safe side, clown fish (tomato), and bubbletip anemone. Also, some mushrooms (purple) and green, are nice to have. Before you buy the light, might want to post what you are planning on keeping, and then we can go from there