Hey David.. Grins one of our resident Gurus put
this (<- click linky) together a while back.. A bunch of us have been helping a couple of others put together nanos.. Since you are new my first suggestion is to read Robert Fenners - The Conscientious Marine Aquarist book. It is going to answer a ton of questions. But to answer the above
These are my personal opinions.
1) Ditch the FW substrate. Honestly it has no business in a SW aquarium. Find yourself some nice aragonite sand (sugar sand or oolite sand). No bigger than 1.2 microns (um).
2) With a 10 gallon you are going to be very limited. Unlike FW, SW fishies need their space and are very territorial even if they are labeled reef friendly. About the only non-territorial fish I own are my Pajama Cardinals.
3) If you have a good LPS you should be able to get Live Rock and Live Sand there. If not I suggest Live Sand from Marine Depot and Live Rock from Premium Aquatics personally, just due to the reviews their LR has gotten from my trusted sources.
4) Lighting.. You need to decide what your going to do with the tank first. FO (Fish Only), FOWLR(Fish Only with Live Rock), Reef (and what kind of reef, SPS, LPS, Softies or Mixed). In a 10 gallon your going to be hard pressed to do a lot of mixing but it is possible to do some.
5) Power Head - again flow is going to be dependent on the type of tank you want to keep.. FO - 10 x the total gallons of the tank in water turn over per hour, FOWLR - 15 to 20 x, Reef 20x to 30x
6) Saltwater should be mixed in a separate container outside of the aquarium so that you can get it completely dissolved and to the 1.026 specific gravity that you are going to need. Some reef keepers keep it lower and with a FO or FOWLR tank that is actually ok.. But again if you plan on corals you need to keep it as close to ocean parameters as possible. You should also use a power head and heater to make sure it completely dissolves and is the same temperature as your tank water before doing any water changes etc.
7) You didn't ask this but I'll offer it anyway.. Test kits, your FW ones won't work. A good hobbyist kit is an API Master kit. Your also going to need something to test alkalinity and I suggest the Salifert Kit for that. If you plan on having corals you'll need a calcium, magnesium and other test kits to ensure proper water quality..
8) - Again an addition - RO/DI water from either you purchasing one or getting it from your LPS. You can get it premixed with salt, I suggest without salt that way you control what you put into your tank.
hth - and again I really suggest you read that book. It has a wealth of information that is just two thumbs up for any SW beginner.
