Saltwater Aquarium Setup
What do I need first? 
 A saltwater aquarium cycles differently than a freshwater aquarium. Today’s modern aquarists predominantly use live rock (which is rock taken from the ocean) and live sand to help not only cycle the aquarium but also process waste products on a constant basis. Your aquarium should be stocked with approx. 1 lb. to 1 ½ lbs. of live rock per gallon of water. If your aquarium is stocked at a reasonable level this will allow most nitrate that the aquarium produces to cycle out. A saltwater aquarium will go through many different cycles. They usually come as ammonia-nitrite-nitrate-diatoms-algae-hard algae (coralline algae). If water conditions are poor or cheap sand is used it could take up to 6 months for the last stage of diatoms-algae to occur. This is because free silicates in cheap sand will feed the diatom bloom for many months. Also, if water quality is poor the algae stages will be a big problem until the source of the food is discovered. Hard algae are desirable and a sign of a healthy aquarium. Hard algae come in a range of colors from pink to red and purple etc.
If water quality is poor then you should purchase a water purification system. Reverse osmosis systems and deionization units come with a variety of capabilities. The equipment attaches to your faucet and removes a number of substances like nitrates, phosphates, toxins, heavy metals, and chlorine. These units can be expensive, but if your water is bad you’re going to need it.
Salt:
Your aquarium will be greatly influenced by the quality of the salt you use. There are many brands available but don’t try to save money by purchasing cheap salt. There is very little difference in the more expensive salts but a big difference in the low end. Kent, Instant Ocean or Reef Crystals are all good choices. Buying a bulk 55 lb. drum of salt rather than buying it in small bags is a good way to save money. Mixing salt is done differently by everyone. We suggest that you mix your salt in a spare aquarium or water drum because when first mixed salt is very caustic. If you are just starting out and the aquarium is TOTALLY EMPTY then you may mix the salt you need in the aquarium. Get the temperature of the water to 81 F (or the hydrometer won’t work properly) then add salt till the specific gravity hits 1.015. Leave this mix for 24-36 hours as different compounds in the salt mix at different rates. After 36 hours all the compounds should have mixed well and you can retest the specific gravity. It usually will remain the same but can increase over time as all the salt mixes into the water. Then slowly add salt till your hydrometer reads 1.022 and stop there.  Use a power head to circulate the water for a few days. The pH can be quite high when the salt is first mixed, and it can also give a false reading for ammonia so don't be alarmed if this happens. You should plan ahead for water changes by mixing your salt a day or two before the water change to prevent problems. Salt mixing for water changes is usually done in spare buckets, Rubbermaid tubs or any food grade plastic containers. Mix the salt in exactly the same way as the first time. Get the water to the right temperature then add the salt, check the specific gravity of the new water against the old water for compatibility and once they are identical set the new mixed water aside for a day or two. Keep an eye on its pH, and once the pH of the new mixed water is stable its safe to use. This usually takes about 48 hours, sometimes longer for amounts of 50 gallons or more.
Lighting:
Your lighting will determine what you can keep in the aquarium. Light is not only used to view the fish but its also used as a food source for corals so the lights must be powerful enough to supply the demand of what you wish to keep. Fluorescent lighting is considered by many to provide optimum lighting for fish only aquariums. Soft corals will demand either a small bank of several fluorescent tubes or a power compact fluorescent as these deliver more light per watt than a normal fluorescent tube will do. Hard corals will demand several power compact fluorescents or the high end of lighting which is halide lighting. Aquariums are calculated on depth for the amount of light needed to penetrate the water. To supply lighting for food it must penetrate the water to feed effectively. For every 100w of halide light supplied the penetration is approx 12" so a 15w light tube is really only going to penetrate about 3-4" The spectrum of lighting is also important. Freshwater aquariums use anything up to 6500 Kelvin’s, but a saltwater aquarium will suffer massive algae growth and look washed out with such a yellow light. Reef aquarium lighting is generally 10,000 Kelvin’s in temperature which gives a crisp but not yellow light. For a deeper look to the aquarium then 14.000k or 20.000k halide tubes are used or a combination of  them all. The bluer end of the spectrum is used for corals to convert sugar into food more than the whiter end so if you do use 6500k tubes then you should supplement the  aquarium with 50.000k dedicated blue tubes.
Water Flow:
Flow is mainly produced by means of power heads. Reef  aquariums have quite a bit of flow to not only stimulate the action of waves but the added flow also helps with water quality, as the more water is pushed by and through the porous live rock the faster it will be able to process waste products. How many power heads you need depends on what type of aquarium you have.  A fish only aquarium will have substantially less flow than a reef aquarium, especially if there is less rock in the aquarium. Structures in the aquarium will dissipate flow considerably so additional pumps may be needed to stop any dead spots from forming within the aquarium. A good rule of thumb is to try to cycle the aquarium’s water every 10 minutes through power heads. Sometimes this will need to be increased depending on the structure and layout of the aquarium.
Mechanical Filtration:
Saltwater aquariums are usually very well filtered. This is usually done by skimmers but some aquarist's like to use some form of mechanical filtration. Any type of filter can be used but its good to remember that any floss or filter material should be rinsed in tap water every 3 or 4 days to kill the bacteria that’s living on them, otherwise they will become biologically active and start to produce nitrates in massive amounts, with negative results..
Chemical Filtration:
This form of filtration is used more often than any other. Activated carbon in your power filter absorbs dissolved molecules from the water by trapping them. This will add a sparkle to the water and will remove impurities and phosphorus from the water. Activated carbon must be thrown out and replaced every month.
Live Rock:
A saltwater aquarium filtered with live rock will cycle ammonia-nitrite-nitrate-nitrogen gas plus consumption due to anaerobic bacteria in the cores of the rock. The advantage of live rock’s natural ability to cycle water is the reason you should use live rock as part of your filtration process. Live rock is large hunks of rock that have been taken from the ocean. It is not only full of billions of bacteria spores, but also home to thousands of small critters such as hermits, sponges and tube worms. In fact the list of life on them is huge which is why we pay so much for hunks of rock that look dead. There are two types of live rock available the first is uncured which has just been removed from the ocean and contains a lot of life. On the down side it also contains quite a bit of dead bacteria and critters so it is going produce ammonia when added to the aquarium. Cured rock is the second type available and is more expensive because of the time it sits in vats of water with regular saltwater changes to remove the ammonia. If you use sufficient amounts of live rock then mechanical filtration isn't really needed. The live rock will do a great job filtering the water for you as long as there is sufficient flow in the aquarium and the rock is cured to a high degree. 
Filtration:
This is one of the biggest parts of your aquarium you want to get right. Filtration in a saltwater aquarium should make the water so clean that you could drink it. (Minus the salt) You wouldn’t want to try this of course. In a freshwater aquarium there is a definite cycle of ammonia-nitrite-nitrate, but in a saltwater aquarium we are able to go another step and process nitrate to its gas form. By using anaerobic bacteria and understanding what conditions this bacteria need to thrive we can have a virtually nitrate free system that is completely natural.
Berlin System:
The Berlin system is what many aquarists prefer because with a good protein skimmer and live rock most if not all of the aquariums filtration needs are met.  A concentration of 1-1 1/2lbs of live rock per gallon of water a good skimmer and there is no real need to purchase expensive external filters. The live rock will cycle an aquarium and carry out all stages of filtration, the only thing that's really needed to make the Berlin system work well is good water flow. Water needs to be pushed through the rocks in order for the bacteria to have access to it. It’s also good to have a deep sand bed to provide total coverage from all angles.
Sumps
A sump is a smaller aquarium which is either kept to the side or the bottom of the main aquarium. It provides an area to put all of the less attractive equipment such as heaters and protein skimmers and if enclosed in a cabinet it reduces noise. The main reason for the sump is to increases the amount of water in your aquarium which allows you to have more fish without being overstocked.
Testing the water can be done at any time. pH should be done just before the lights come on and just before they turn off at the end of the day because photosynthesis will raise pH Water tests are the key to maintenance and preventing problems. So always test frequently. Algae are a problem that comes from a number of sources. Using tap water, overfeeding and incorrect lighting or old light bulbs are some of the most common sources. Algae blooms in one area of the aquarium means that something probably has died in that area and is releasing nutrients into the water and causing a local bloom. You should try to locate what has died and remove it if possible. That may mean moving rocks and corals to find it. 
Wet/Dry Sump Filters or Trickle Filters are designed to maximize the exposure of the aquarium water to beneficial bacteria and air at the same time. This allows the ammonia to be cycled more efficiently. This type of filter is used only for fish only aquariums.
This is by no means a complete study of setting up a saltwater aquarium. You should gather as much information as you think you need to feel comfortable before starting. There are many great books and info is readily available on the Internet. So enjoy, and happy aquarium keeping.
ALSO SEE  CREATING A REEF TANK