Ok, I've done this for years, and I can get things done cheap. I set people up all the time who are on budgets, and you can keep a nice well kept saltwater aquarium for less money than most people think.
You just have to be patient. There is a saying that works well for saltwater, you can have it good, cheap, and quick, but you only get to pick two...
cheap and quick isnt good
good and quick isnt cheap
good and cheap
The facts are, good and cheap takes time. Keep in mind, cheap is a relative term...
The best way to setup a saltwater aquarium cheaply is to focus on the essentials.
Tank
Sand / Rock
Salt water
Heater
Water Movement
Lights
Life
The trick to keeping the cost down on these is to buy used.
Tank:
You are getting the tank free, and that's great! As mentioned above, if it is in good shape its worth it. If it's all scratched up or leaks, its not.
Sand / Rock:
Typically you can get this when someone is shutting down a tank. There is a huge hassle when buying used sand. You have to clean it, and let it re-cycle before putting fish or coral etc in your tank. Its cheap, but again... it takes time! Live rock can be gotten pretty easily around $2/lb and you should start with 50lbs (In my opinion) this will be the bulk of your initial cost.
Salt water:
The cheapest way to start this is buy buying a case of saltmix, (you want at least enough for 100g. You need to have enough to make all your water, and some to do water changes in the future. You should be able to get salt for around $50-60 for a 200g mix case, or 160g mix bucket. Then go to your local grocer and buy r/o water.
Heater:
I suggest buying two used ones (new if you have the $$$) and set one a degree or two cooler than the other. This ensures if one fails, the other will kick on and keep everything from dying. You don't need two right away, so feel free to only buy one for now.
Water Movement:
Find a used Maxijet 1200 or a hydor korilla 4. Put it on one and face it up toward the top of the water. This is aerate the water and mix it around at the same time. Eventually you will definitely want to add more, and position them better, but this works for a starting place.
Also, put your heater in the corner that the pump is pushing the air towards, as the water crashes against the side of the tank, it will be forced downward and the heated water will mix better with the colder water settled at the bottom of the tank.
Lights:
Anything cheap will work for now, you are not adding any coral for a while so save your money, and keep an eye out for something used. Just make sure the bulbs are newer, and meant for saltwater. You don't want to start out with a huge algae problem.
Life: (the fun part!)
The bacteria you need to keep the cycle going will be in the sand and rock. The bacteria is what makes "Live" sand, and "Live" rock...
After you setup the tank with everything above, wait till the next morning. grab a sample of the water, and take it in to your local fish store and ask them to test it, and write the parameters down for you. You should do this at least every other day for the first week to watch the tank cycle and find balance. Most fish stores should be ok with this, they know you are new, and you will probably buy the fish from them if they build that relationship with you. If they aren't willing to help, or offer advice, GO SOMEWHERE ELSE!
Once the tank is cycled, buy a pair of ocellaris or percula clownfish first. Do not buy "damsels" Clownfish are in the damselfish family, and are just as hardy but far less aggressive and more likely to get along with other fish you add in the future. If you absolutely hate the look of clownfish, do a little research to find other non aggressive hardy fish that you like. You only want to add one or two fish at first, so don't go and buy a school of chromis or anything just yet...
The trick is to keep a well balanced reef, Bacteria is your biggest filter on a saltwater tank, and the most important. Fish will create waste that is toxic and will need to be broken down into less toxic material and then removed from the water. At first, this will be done through the live rock and sand as well as regular (I suggest weekly 10%) water changes.
Don't worry about the sump, protein skimmer, reactors etc just yet. You have just the basics here, and we've been keeping saltwater tanks without those things for years.
As your tank finds balance, you can add things, but make sure you keep it balanced. for example,
After you add your first fish, and the tank balances out, then add some snails. Give it some time, and add a shrimp or a crab...
ALWAYS MAKE SURE THEY ARE SAFE TO ADD. If you add something that isn't reef safe, and then add something from a reef, just count on loosing it. Back when I worked in the fish business, people would always bring in chocolate chip star fish that another store sold them. This always ticked me off, and a few stores got to hear my Opinion on their business ethics and quality of staff... long story short, people would buy them for their reef tanks, and the things would devour all their coral almost immediately! Our tanks were littered with them in our sumps...
Be smart, and research what you want to buy before you buy it. If you want a reef tank (an aquarium with live coral) then make sure you buy only "Reef Safe" creatures.
Also study out sensitivity and toxicity of the creatures. Another popular problem I saw were sea apples, cucumbers etc... People love them because of their colors, but when they are ticked, or die, they ink... and the ink is toxic!
As your tank grows, so with its needs. That's when you will need to upgrade things, and help keep the balance. The only time you need to add additional filtration equipment to your system is when it isn't properly balanced. This is where I will probably get flamed, but everyone has a right to their opinion and in my experience this is the case.
I currently run a network of tanks totaling over 500g and do not run a skimmer, or a reactor of any kind. That being said, I have roughly 700lbs of live rock spread throughout the system and less than 20 fish. I have 30-40 peppermint shrimp ~20 emerald crabs, hundreds of snails and astrina starfish, lots hermit crabs, mini brittle stars, etc... to put it in short, the system is well balanced. I do have a skimmer I can add to the tank if I would like, but I haven't ran it in a few months, and took it out because it was taking up space. I used to only run it a few times a month.
I do however suggest getting a protein skimmer when you can afford it. It will help you remove organic proteins (waste) from your tank and allow you to have more fish.
Also on your list should be lights that can sustain the coral that you want to keep. One of the best things about saltwater is the coral that you can keep in the tank. There are tons of threads on here discussing what lights are best, and why. Read them and better yet, visit some reefers houses to see their tanks, and make up your own mind on them.
You will also want to upgrade to a sump eventually. Sumps are great places to hold things like skimmers and heaters and other equipment if you choose to add them. You can also hook them up to auto top offs so you don't have to add fresh water all the time to keep your tank where it should be. Sumps add extra space to put more live rock, and even macro algae to help clean the water. The also aid in the aeration of the water and the return will increase the movement of water in your tank. In my opinion, a sump is the best upgrade you can give your saltwater tank, and you will benefit greatly from having one.
All in all, the best way to get your equipment for cheap is to buy a setup from someone who is either getting out of the hobby or upgrading to a bigger setup. Just make sure its a good deal, and the equipment will allow you to do what you want to do.
Most important, read and research as much as you can, and don't be afraid to ask questions. Also, ask questions about the answers you got from the earlier questions...
Have fun, and happy reefing!
