With all aquariums there are key decisions to be made before making a purchase including size, stock and style of the aquarium. The most popular choice of marine aquarium is that of a reef, which allows hobbyists to keep a larger and diverse selection of stock including coral, shrimps, hermit crabs etc. There are species that will eat corals and small invertebrates as part of their natural diet so these specific fish are not suited to a reef aquarium. Individuals that decide to keep these fish do so in a fish only system.
Having decided the size of the aquarium you want to keep (as always bigger is better) determining what style of aquarium and stock to keep is paramount. Essentially marine aquariums provide the foundation for a larger variation in stock than any other aquarium, so unless you specifically want to keep a non-reef compatible specimen then a reef style aquarium would be highly recommended.
Aquariums designed specifically for marine often benefit from been concealed units housing all the equipment in sump systems or fake backings. This type of system won't necessarily provide a better environment for your stock although it does benefit from making a neater looking aquarium than converting a predominately tropical aquarium.
When you look at a marine aquarium the odds are you will be presented with a vibrant, active and mesmerising piece of furniture, which appears to be filled up with purple obscure looking rock. This rock is known as live rock and has a bacterial surface that provides biological filtration for the entire system. In a freshwater aquarium biological filtration is taken care of by the internal or external filter, in a saltwater aquarium these types of filters are used for mechanical filtration only as the amount of biological filtration they provide is minimal. There is a process to introducing stock to a reef aquarium. After the aquarium is set up it is normally left running for a week to let the live rock, protein skimmer and filters purify the water. Subject to the water quality you can now introduce the cleaning crew, built up of snails, hermit crabs and cleaner shrimps. They not only look decorative but also perform a duty by circumnavigating themselves around the live rock, eating any micro algae that covers the bacterial surface of the rock and restricts its function, to filter the water. A week from now it is time to introduce your fist fish and every week from this date you can introduce another till the tank is at its full capacity. Corals are more sensitive to toxins so it is recommended that they are introduced after the aquarium has been running for 6 week and onwards, there is no specific timescale for this as it is all dependent on water quality but this gives an approximate guideline. Corals can actually help maintain water quality by absorbing some of the toxins produced by fish as a bi product of their waste.
All in all Marine aquariums provide the most stable aquarium due to the live rock containing so much bacteria that even if problems such as drastically overfeeding were to occur it would take a very long time for the water to degenerate to a problematic level. So providing you do your 10% partial water change every 2 week, (we stock pre mixed salt water) and have your water tested at the time (a service we provide free of charge) we can point out problems before they occur, prevention rather than cure.
After the aquarium is set up it is critical that patience is spent introducing fish. You have to spend months stocking an aquarium to allow the bacteria to develop that biodegrades fish waste. This bacterium develops slowly to ensure the pollutants don't outbalance the bacteria only a couple of fish a week should be introduced.
Also when placing new fish in the aquarium they should be left floating within the bag for 10 minutes to acclimatise them to the temperature, then the bag should be opened and pegged to the side of the tank.
Now you should systematically add small volumes of your tank water to the bag over the period of an hour till you have 3 times the amount of water in the bag than you did to start with, this acclimatises the fish to the aquariums chemical conditions.
Now carefully net the fish out of the bag and place it in your aquarium. At this point turn your lights off not to stress the fish any more and leave it a good 6 hours before disturbing the tank. Take note that it is often necessary to pour some water out of the bag before starting this process as you remove the bag of water after and it can result in a lot of displacement.