The physical requirements of the location
The very first thing you need to consider when starting your first tank is where it is going to be placed. There are a number of considerations that need to be taken into account.
The weight of water
Water is very heavy, over 8 pounds per gallon. When you include the weight of the decorations and substrate, it often rises to at least 10 pounds per gallon of aquarium capacity. That is the figure I always use to decide where I am going to place the tank. The location must be able to handle and accept the weight of the tank for a long period of time.
Because of this, I never recommend using any type of furniture to support the aquarium other than a manufactured stand that is designed to support and distribute the weight correctly. Even a 5 gallon tank will average at least 50 pounds, sitting on a table or other flat surface for extended periods of time can slowly cause the support to shift, which for a glass box, that can be deadly.
Anything over 10 gallons should always have a properly manufactured aquarium stand, and in many cases 10 gallons is already stretching the support over time. Originally aquariums were made out of glass plates held in place over a slate bottom with stainless steel frames. The box was caulked and expected to leak in a few years as the caulking dried out and weakened. The support had to be perfectly flat; flex and warp resistant. Any warping could easily cause the slate bottom of the glass plates to crack.
Aquarium Construction with Silicon
Then came the true savior of the aquarium industry - silicone. It is light, extremely strong and holds its bonding strength for many years without getting dried out or brittle. In fact it is so strong, aquariums are now made solely of glass and silicon only. A true glass box.
Many aquariums come with a plastic frame. This is not required for the integrity of the glass box, the silicone does the job by itself, however, to more rapidly and reliably manufacture an aquarium quickly, as well for aesthetic looks, often an aquarium will include a top and bottom plastic frame around the rim. The top frame is often useful for securing a proper cover over the tank to reduce evaporation, hold a lighting fixture and keep nervous fish from jumping out.
The bottom frame was used to insert the edge of the glass side into and hold it into place while the other sides were assembled. This type of construction does allow for a small airspace under the bottom of the frame, the glass was put into the frame and creates a floating bottom allowing the frame to flex very slightly if the support plate shifted and settled a bit over time. The price of plastic has risen and many manufactures have moved to frameless tanks.
The problem with frameless aquariums is that, while glass is very strong and durable, it is weak on the lateral dimensions. If the support shifts from level, the pressure on the lateral edges can easily cause a stress crack in the tank without any outward appearances or warnings.
Use a properly manufactured support stand
for any tank you install.
Furniture may appear sturdy and flat, but it often has places where heavy items will cause it to shift, usually enough to cause a stress crack on the plates without warning. Repeated water exposure over time can also cause the wood to expand, crack or warp. Purchase a manufactured aquarium stand for the tank that you decide to purchase. Otherwise, you are setting yourself up for a flood from a cracked tank. The only real support that is required is the corners of the aquarium. They must be supported and level at all times.
Always place your aquarium on a supporting wall
Just any wall will not be best for an aquarium. You should be using a supporting wall, one which is part of the actual structure of the room. Outside walls are usually supporting walls. Inside walls sometimes are, but they can also be much more flimsy supports for the stand.
Older houses often creak and bounce as you walk by, if this occurs, the area is not a very good one for an aquarium installation. If the floor shakes as you walk by, the effect will be even more amplified when an aquarium is placed there. When deciding where to place the aquarium, make sure the wall and the surrounding area is as solid as possible.
Stay away from windows
Light in the aquarium is extremely important. Natural light is one of the worst things to allow into an aquarium, the only light that should enter the tank is from artificial lighting that you control. There are two reasons for this. Natural light is powerful, it supercharges one celled plants called algae and lets them explode in population quite easily. If natural light gets into the tank on a daily basis, the algae will become a constant problem for the clarity of the water. It will also coat the sides of the tank. You want to look at the fish, you want the plants to grow naturally and sunlight simply throws a wrench into that plan. Find a location, on a supporting wall, well away from ambient sunlight. It is much easier to control the look of the tank when it is not allowed into the water.
Sunlight also adds a lot of heat, as well. When an aquarium is placed in direct sunlight, the water in the system can rise and fall a few degrees every day. That constant adjustment the fish must make with their metabolism can begin to take a toll on their life systems. They are cold blooded, poikilothermic, meaning their bodies are at approximately the same temperature as the water they swim in. If it rises and falls a considerable amount each day, their metabolisms are stressed and opened to possible disease and illnesses that can be avoided by ensuing the only lighting in the aquarium is from artificial lighting that is totally controlled by the aquarists.
Stay away from Heating and cooling ducts
In the same way that sunlight can cause temperature problems with an aquarium. It is very difficult to regulate an even and steady temperature on an aquarium that is situated over an air conditioning or heating duct. The same applies for ceiling outlets as well. Be sure there is no chance that the heating and cooling of the home in anyway is exposed to the aquarium.
Summing up
Water is very heavy, a 5 gallon tank, on average weighs 50 pounds, a 100 gallon tank can weigh up to a half ton! All tanks over 10 gallons should never be put on standard furniture, they should always be placed onto specifically manufactured aquarium stands. If not, there is a very good chance that the tank may suffer a stress crack in the sides if the support shifts. Modern aquariums are made with glass and silicone sealant, making them very strong, but shifting the bottom plate can result in the most vulnerable area of the tank, the edges, being so stressed that they can crack.
Tank location is vital, make sure the tank is placed on a load bearing wall, non-structural walls and islands have a tendency to move and wave as people pass by, causing those ripples to be felt in the tank and adding extra stress on the glass plates as time goes by. Be sure that the tank is placed away from all sources of heat and cold, especially the chance of natural light physically entering the tank and having a chance to spur the growth of algae and possibly overheating then cooling the tank on a regular basis. Uneven temperature over time stresses the fish and it is much simpler simply to avoid placing the habitat in locations where heating and cooling ducts, as well as windows can affect the environment your precious specimens must reside.
