the first few responses on this thread had me rolling i was laughing so hard.. the myths of the expenses of saltwater tanks are truly funny to me now that I took the plunge (yes i did have a larger saltwater tank for a while im not saying all of this off of the 10 gallon reef i have now I set up a friends 75 gallon and I had a 46 for quite some time before deciding i missed freshwater) - In all honesty you have to decide a stock and go from there. FOWLR tanks (Fish Only with Liverock) are not too horribly bad so long as you don't jam the thing tight as you possibly can with big fish.
Needs -
Approx 30-50lbs of live rock for best results, typically can find on craigslist for $2-3 a pound, this is the most expensive part
Protein Skimmer - There are some affordable options out there under $100, in a fish only tank or even a tank with soft corals, it is not a necessity as long as you do your water changes
15lb bag of aragonite for a thin layer covering the bottom - $20
Bucket of Salt that will last your initial fill and many water changes to come - $50
Hydrometer - $10
Powerhead to get some flow, for a 55 FOWLR one with 600gph capacity will be sufficient, get a marineland maxi-jet, theres $20 or so
Canister filter CAN be used, just make sure to clean it regularly and you already have a heater
- right there that's the main hardware for your tank at it's most basic. you're looking at $60-150 in rock, $20 in sand, $20 for the circulation pump, and $60 for hydrometer and salt bucket that will last you a long time. That's only $160-$250 to have that thing running saltwater, a far cry from $1k+. If you have a local LFS, they typically will test the water for free. If you don't mess with corals, the fluorescent bulb you have on the tank now is sufficient. As far as maintenance costs you will need to dose with calcium and alkalinity boosters, both combined will run you about $15. The most expensive part of the entire process is your clean up crew (crabs snails etc) but there are websites out there where you can get them for pennies on the dollar, where you may have to pay 2-3 bucks at a store you can order em literally at .15-.50 cents a piece. Do it smart you're lookin at another $50 tops. As far as fish keep it easy, a pair of clowns is only gonna run $30-40 bucks, a lionfish isn't a great choice for a 55, fish gets too wide, dog-face puffer you would also wanna avoid most likely. As long as she doesn't choose some ridiculously expensive fish or start trying to throw tangs or angelfish in there first thing there's no reason for this to surpass $400, and in all honesty it can be done for under $250.
Shop Smart and this is very doable. Listen to your local LFS and buy everything under the sun and then your wallet will cry. Best of luck whatever you choose
