tank conversion

i have always kept cichlids, and lately have been thinking of changing my 55 gallon to salt water. what would i have to buy for this? what kind of daily/weekly maintenance is needed?

ok for one welcome to the dark side lol i did cichlids as well for a long time and i loved it and still do but now saltwater is my addiction. So let me help ya out here
As far as your tank goes, good size to start with
Things Needed( if not already on tank)
1. Live Sand
2. Live Rock(try and find someone that has some in a tank that is already established)
3. Salt Mix or you can got to a local pet store that sells water by the gallon that is already pre mixed (the stuff they mix themselves not the expensive little jugs on the shelf lol)
4. Good lighting that promotes growth (HO lights or Bright T5)
5. Hydrometer ( for salinity/ gravity)
6. Saltwater master test kit or Reef kit depending on what you are doing)
7. Filtration now this is your choice, most people use wet dry systems but you can also use hang on the back as well)
8. Power Heads/ Circulation Pumps ( lots of flow and movement is a good thing)
As far as maintenance goes you have to check the water and do water changes as you would with cichlids, and keep up with it, i found it helpful to make a chart or a notebook for when i do tests and water changes, to see what varies in the results. Once your tank has been running for a few weeks and you have been checking your water you will notice brown algae starting to form(good thing) so dont freak out its normal, with saltwater the key is BE PATIENT cause your tank will look worse before getting better, a trick a guy showed me is that when your brown algae form go out and buy a new tooth brush and lightly scrub your rocks in the tank, now you may have to do this a few times before it goes away and then you might get green algae which is also normal but sucks lol, and at that point if your water checks good go get you a few turbo snail to start cleaning your tank for you, and feel free to add some damsels in there around week 2 of running(forgot to add that in the beginning lol) and that should get you started for the most part im sure i missed a few things just let me know any questions you got and i will help ya the best i can

for the "brown algae" aka Diatoms dwarf cerith will clean them up in no time.
Damsels are very aggressive, I would recommend starting your tank with Chromis instead. there are a bunch of conversion threads here and these questions have been answered over and over just look for the threads.
as far as setup it all depends on what you want and your budget, like do you have or plan to go reef ready or a standard tank? are you planning a reef or a FOWLR?
once a reef/FOWLR has marinated and become stable the maintenance is easy. I do weekly sometimes bi weekly small water changes and clean the glass every few days along with top offs. I try to do water changes on all the tanks on the same day so for example it takes me 2 hrs to do the water changes and empty skimmer cups and clean my glass on a 180G,RSM 250,RSM130 and a 40 breeder the most time consuming part for me is getting my water change water ready because I like to make sure the salt has had time to dissolve and mix atleast 24 hrs before I use it. I use a 55 gallon Brute can the day before I plan a w/c to do this then when the water is ready I use a pump to pump out the old water then pump the new back in.

i havea 55 reef..

hob emperor 400
2 powerheads bout 150gph apiece
skimmer(aquired after about a yr and a half)
50 lbs LS 60-65 lbs LR(i got this over about a year span also)

you can do a base rock and LR combo its cheaper then getting all LR to start out with i stated with like 25 lbs base and like 10 lbs LR

as far as care goes lol im lazy with mine i top my tank off with fresh water once a week or so, i have no lid so i have alot of evaporation but it keeps the temp down/stable, do like 15% water change every 2 months hey it works for me.. i know people who never do water changes and their tanks are beautiful and have been set up for many years..i no people who do like 5 % a week habitually..every tank is different and it really depends on how much time you want to spend workin on your tank honestly..for some reason my "minerals" like calcium magnesium etc is always at peak levels so i very rarely does or buffer the tank.. buti dont have to either

LS
LR
powerheads
strong lighting (for reef. not a must with fish only)

HI It's not hard to convert from freshwater to saltwater.. i have done but had to take my saltwater do to some person health stuff... If you need help let me know I'm in plano.