2.1 The Aquarium:

Size:

The biggest one possible will give the stablest water conditions. Nothing against a small tank, but they actually can be more work and the temptation to overstock is higher. A larger stand/ cupboard will house all the technical stuff (and nonsense) you acquire over time.

Shape:

A rectangular one is cheapest, especially if it is an 'off the shelf' size, though these usually stop at 50cm height and depth being for the freshwater market.
A panorama type can look good, but you have to keep 5 sides free of algae (including the calcareous variety). May look less like a big box.
A delta is ok for the corner- but will the lighting fit over it. No place for a sump filter!
Rounded front glass- how are you going to clean a curved inside surface when all razor blade and magnet cleaners are designed for flat ones?
Depth (i.e. front to back) is important. Seawater is denser and has a higher refractive index than freshwater. This makes a 40cm deep tank, which may be quite adequate for freshwater, look to have no depth at all! If you have room, 60cm is ok.
White glass gives better colour. At least when I look at my aquarium I'm convinced that it does. Naturally it's dearer, this is because the silica used to manufacture this glass has to have the usual iron oxide impurities removed, it is these which give normal glass its green tinge- just look at a thick piece of glass end on.
Perspex/ acrylglass- They aren't widely available in Europe and are at present very costly, I suspect due to their exclusivity more than their actual manufacturing cost. Can the scratches be easily removed or not?
More info at http://www.schuran.com/index_seawater_e.htm

Home made tanks of wood, PVC, cement, glassfibre or other materials with a front glass panel- I have seen good ones. There are web sites with instructions. Don't think it will save you money. Hard work and costly if you make any mistakes. Usually need a special 2- component coating on the non- glass surfaces, which isn't practical to apply indoors unless you have a large workshop with mechanical ventilation.


You should choose an aquarium with adequate glass thickness. Whilst glass that is too thin may not actually give way, it will certainly bend, which is why many tanks, mainly those intended for freshwater use, have a wide middle brace. If you do have a middle brace, and want to use this tank, plumbing for filtration should be your next thought

If you are having the tank custom made, then strips of glass along the lengths of the tank are good, but a middle brace may well be in the way of the lighting for a reef system. 10mm glass is then ok for an aquarium 100cm long, I would go for 12mm glass for 120 to 150cm length, then increasing above this. Your specialist dealer will advise you.
"Off the shelf" complete marine setups are also ok, but you have to be satisfied with the technical equipment which comes in the package.
Converting a freshwater system may seem tempting, but you will be faced with many compromises, and a tank which is probably a few years older than you remember. If you think you bought it 5 years ago, get out the receipt/ guarantee slip if you still have it- chances are it is more like 8. But this isn't a discussion of human nature......... You will also, if you want to put your filtration in a sump, need to drill the glass, this is not for the faint hearted- you cannot afford any mistake here.

2.2 Siting the Aquarium

Even a medium size aquarium is quite heavy even when using 10mm glass.
For example, a 100cm x 60cm x 60cm aquarium will weigh about 80Kg empty.
Add 300 litres (KG) of water, plus rockwork and you have something which needs siting properly.
You will have probably thought of a stand (home made or not). The stand's construction will influence how you site the aquarium. Most commercial stands are effectively cupboards with coated mdf or chipboard panels used in their construction. You might then find that the underside in contact with the floor just consists of the outer frame. This will apply all of the weight to small areas of the actual floor. The stand must also be level- this means your floor should be level. If it isn't, you will have to pack something under the stand to fix this.
The wall directly behind the aquarium should be a load- bearing wall.

2.2.1 Wooden floors

By this, I mean wooden beams with wooden floorboards nailed down on top. Whether the floorboards are bare, covered with carpet, or indeed anything else, this will make no difference.
The tank's stand or cupboard should stand on a plinth to spread the load. An adequate plinth can be made from marine grade plywood (this won't start to swell or fall apart at the first water spillage). The long axis of the aquarium should be sited so it lies parallel to the flooring. This is so it is at 90° to the joists/ beams underneath. You should see from the rows of nails going through the floorboards where the beams are. Try and site your aquarium so it stands on at least two beams, to spread the load. This means that if you want to put the aquarium next to a wall, your choice is limited to 2 sides of a rectangular room.

Has the floor been sanded- if it is waxed or varnished, it almost certainly will have- it is in the nature of things that the sanding treatment will not have taken as much wood off next to the walls. You may therefore need to leave a larger gap than you intended between the back of the aquarium and the wall behind it.

Beams are usually suspended between 2 walls over a length of 3-4 metres. The walls that these beams lie on are bearing the load. Load- bearing walls are generally thicker than non- load- bearing ones, in modern housing, the latter are often made of a wooden frame with plasterboard surface. On of the load bearing walls is often also an outside wall.
The further away from the support the aquarium is, the more it will exert a load called the moment tending to make the beam move- think of the support point as a pivot, and the tank exerting a levering action- think of wheelbarrows and seesaws.

2.2.2 Solid/ suspended floors

This includes parquet and laminate flooring on a concrete base, but not a floor skimmed over floorboards. Most stands/ cupboards will be able to be stood directly on these floors, but just as the sanded floor tends to go up at the edges, a concrete floor is not guaranteed to be flat and level. You can pack strips of wood or plastic under the stand (before you put the aquarium on it) using a spirit level to ensure it is absolutely level.

2.2.3 Unlevel Floors

What you need is a plinth. Can you buy a plinth? No! You need plywood- waterproof grade. MDF will not be good for this, since it is affected by water. The plinth should be cut to 2cm more than the width and length of your cupboard. You then can use an adhesive spray and cut pieces of  the plastic foam sheeting normally used under parquet flooring. If you cut the first piece to cover the plinth bottom, you can then cut the next a few centimetres narrower and so on so as to make the underside fit the contour of the floor and make the upper side of your plinth level. You can also fix a single layer to the top. The plastic sheet is robust, will give a little, and should give you a satisfactorily level plinth on which to place your stand.
Although you will probably put a styropor sheet between the aquarium base glass and the top surface of your stand, this surface should not be used for levelling purposes.
If you measure direct from the skirting board and find the floor quite unlevel, measure again starting 5 cm from the edge, this will probably be much better, and you need to leave a little space for cables etc. behind the aquarium.

2.2.4 Wall mounting

A more complicated way of fixing an aquarium. Needs a strong, load bearing wall in good condition. 2 (or more) metal brackets need to be fixed to the wall. A plinth (wood, marble) which should be absolutely flat and level is placed on these, with a styropor layer on top and the aquarium can placed on this shelf. This is a fairly technical solution, and certainly will not be obtainable "off the shelf".

2.3 Equipment Placement

Needs to be unobtrusive but accessible. Skimmers and filters can be placed in the cupboard- style of stand, heaters can be away from animals which can damage the glass or may be burned by using a sump.
Those lucky people with a small room, or garage space behind the aquarium may consider plumbing through the wall. A full- height cellar below may also be ok. All the equipment can then be separated from the viewing area,

2.4 General placement and viewing

Maybe your aquarium will have its own room, or niche, which can be decorated and furnished to suit. Perhaps it is set up in the next room with a wall cutout for the front glass to protrude into the viewing room. If not, is it going to be squashed in between cupboards, wall units and dressers?
Just like a good painting, a decorative aquarium needs space of its own, and you might not want it on the wall next to the TV, if only because it is going to be a light source. You are going to want to sit and watch what is going on- can you see it from your sofa, or comfortable chair? If you can avoid it being where you walk directly past the front glass then it will allow the inhabitants more peace.