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I have an 40 gallon aquarium with the measures 12 inches(width) by 36 inches(lenght) 16.75 inches(height) ...
First check they volume of your tank verses the dimensions. The dimensions don't work out to 40 gal, rather it's about 31 gal.
Either way, that is a large enough tank for corals, so you don't have a problem there.
However, figure out what all the other gear will cost you. Often you'll find that the price of the tank is among the least expensive parts of a SW tank. You may find that it would not cost you much more to include a much larger tank in all this.
As a note, SW is a lot harder on equipment compared to a FW system. I recommend you always buy top quality equipment. This doesn't mean you need to get the most expensive items out there. It does mean that you don't want to skimp to save a few dollars.
Since
@Uncle99 mentioned it, I'll repost my standard lecture #1.
DaveK's Standard Lecture #1 – Advice for people new to the hobby
The very first thing you want to do, before you spend any money on equipment or livestock, is get yourself a few good books on state of the art reef systems. Then read and study them, so you have some idea about what your are doing.
Here are two to start with -
The Conscientious Marine Aquarist by Robert Fenner
The New Marine Aquarium by Michael Paleta <---This book has an especially good section on fish suited to someone starting off in the hobby.
A note on the books. You can often find used copies at much lower prices at places like Amazon. In most cases these are going to be as good as new copies, especially when your first learning.
This is information that you can not easily obtain from the net. While it's out there, it's all over the place, and there is a massive volume of information. There is also a lot of bad information out there.
Once you get that done, plan or rethink your system. What do you want to keep? Do you have the necessary equipment? Do you have the knowledge to keep the livestock you want? Do you have the time to dedicate to keeping a system and it's livestock?
Many salt water fish, corals and inverts often have very specific requirements. Some are extremely difficult to keep alive, even if you do everything right. Before you get anything, research it, and be sure it will work out in your system.
Lastly, you will find that most LFS people are clueless when it comes to SW systems. Verify their advice, until they prove otherwise.
End of lecture
A note on my "standard lectures". On this forum we often get people new to the hobby, or a similar question that is often asked. I came up with the standard lectures as a way to provide some basic information on a topic, and have it something that was fairly short and easy to take in. They also make sure I cover the most important points. It gives people a place to start. I revise them from time to time if I think something else should be included or I have modified my opinions on the subject.
to RS ! Lots of 40 gallon sw tanks... lights that can support corals will be key. Sure some members can advise - I have had AIO Red Sea Max tanks (All-in-one) 30 & 66 gallon tanks.
