The goal of this collection is to give the beginner hobbyist a good idea of what each of the components of the marine aquarium is, and what they do. While not all the components covered in this collection are necessary items, they all do have their function, and can be useful in the right situations. We'll start by dealing with the necessities, and then go to dealing with those that are best practice, and finish with the optional items.

The Tank
This is obviously an essential to the hobby, but what kind of tank you choose will play an important role in your setup. There are many sizes available and even many shapes. Modern technology has allowed us to bend glass and shape it just about anyway your want, and with the option of using acrylic tanks, the shapes and sizes expands even more. So first, lets look at the most popular choice for marine hobbyists; the Reef Ready tank. A tank that is “reef ready” is simply a tank that has had holes drilled in the bottom and overflows installed so that a sump can easily be used. These holes must have bulkheads installed in them to allow the hobbyist to plumb the sump properly. If the hobbyist does not choose to use a sump with this kind of system, bulkhead plugs can be installed instead of pipes and hoses. Generally, however, if you are going to put out the extra money for a drilled tank, you are going to use a sump with it.
Shape is something else to consider. Practically any shape you get will work for a marine aquarium, however there are some that are a little less practical. Hexagon tanks will work, but remember, when you have to start cleaning that beautiful coralline algae, it is going to love all those corners, and it will be a little more difficult to get to. Also, since hexagon tanks are tall rather than wide, they restrict surface area, and thus gas exchange. That added height also means you are going to need a more intense light to reach the lower regions of the tank if you decide to do a reef in it. Again, it can be done, but it is just a bit more difficult. The above points are pretty much the keys for deciding on the shape of the aquarium you want. While they can be nice, odd shapes can be a pain to maintain.
We briefly mentioned acrylic at the beginning of this section, so lets take a closer look at the benefits and drawbacks to this material. One of the biggest benefits to acrylic is that it is much lighter than glass, and is well suited for large aquariums. Most tank owners who purchase a tank that is greater than 240 gallons, purchase an acrylic tank simply because they are lighter, and at that size, they are even more durable. A panel of glass that is 8 feet long and 2 feet high will generally be much weaker in the middle, than a piece of acrylic of the same thickness. While the acrylic will bow easier, it will not break due to the flexibility of the material. The flexibility of acrylic also allows it to be molded into a large variety of shapes without the use of any seams. The seams are another area where acrylic tanks excel. Glass tanks must be bonded together with silicone, and on larger tanks, they have bracing added to the top and bottom to properly support the glass panels so that they do not break. Acrylic tanks have the major advantage of being welded together. Welded seams form a much stronger bond since they chemicals literally melt the acrylic together, thus in essence making all the pieces of acrylic used, one large piece. Bracing will still be required on the top of large acrylic aquariums, but as with the rest of the pieces, the bracing is welded in place creating a very strong bond. Acrylic does have a couple of major drawbacks though, and the biggest of these is price. Acrylic aquariums for some of the more common sizes, are as much as double the prices of their glass counterparts. Acrylic also scratches much easier, so the hobbyist must take care when placing rocks, and cleaning the panels. A piece of sand in your algae brush can make an absolute mess of your expensive acrylic tank.
The final aspect of the tank that we must look at is the choice of size. This is an area of great debate. The size tank you choose will depend on a few factors. The first factor that you must consider is your experience level. If you are just a beginner to the marine hobby, a 10 gallon tank is not likely to be the best option for you as stability of the environment is directly proportional to the size of the tank. The best option for the beginner marine hobbyist, is to get the largest tank you can afford, for the space you have to put it in. This is where we can get back to the shape issue again. If you only have an area that is 2 feet long in which to place your tank, the a taller tank may not be a bad option for you, but remember, you can also add volume to the system by setting up a sump system. Using a continuous siphon overflow is always an option for the use of a sump system if you cannot obtain a drilled tank is the size tank you need. I've already mentioned the other 2 factors, and they pretty much go together. Size and cost are another a pair of factors that must be considered. These usually go together simply because the larger the tank you choose, the higher the cost is going to be for everything. All these factors put together should help you choose the proper tank for you.