Simply because sea water has a strong corrosive action on metal, saltwater aquarium should ideally be made entirely of glass, or plastics. Regrettably, glass tanks of the size needed, and with glass fronts totally free from imperfections caused during moulding, aren't readily accessible. Moulded glass-fibre tanks are becoming accessible, but they're costly. Tanks made from wood have been made by keen fish lovers for a considerable number of years, and you will find some benefits to be gained from this kind of construction, but the most practical is still the standard metal frame, glazed with plate glass. Naturally the frame has to be made from a corrosion-proof metal, or has to be suitably protected, and it's feasible to obtain tanks with nylon-coated frames, or frames covered with some other suitable plastic.
Tanks manufactured from Plexiglas are also fairly suitable except that the material scratches rather effortlessly. For tanks holding over ten gallons of water, the thickness should be i in.-anything thinner than this will bow in the course of time owing to the pressure of water, and when setting up the tank the entire area of the base should be supported. On the other hand, Plexiglas doesn't discolour like most clear plastics and demands small or no maintenance. Cements are essential; they should be non-toxic and if feasible should not be allowed any contact with the water. If a seam of cement is visible at the glass joints, it's advisable to cover the joint with liquid plastic, black asphaltum varnish, or aqua-sealer.
It might be helpful on occasions to use aquariums that had been originally designed for freshwater. This could be done if the seams, any exposed metal, and also the underside of the top if then frame is protected with black asphaltum varnish, or some other suitable insulant.
The aquarium should be thoroughly cleaned and disinfected prior to it's finally filled. Wash the inside thoroughly with clean water, never use soap or any detergents, and then rub the inside with a damp cloth that has been dabbed in table salt. Wash again, and disinfect with a weak solution of permanganate of potash or, should you prefer, wipe the inside of the tank with methylatel spirits, having initial dried the interior. Make certain that the underside of the frame and all corners and seams have been fully treated. Should you have chosen a metal-framed tank, fill it with fresh water for a couple of days. The water pressure will trigger the cement to thin just a little between the glass and frame, and will expose a wider seam inside. Empty the tank by siphoning off, dry the interior and treat the seam with a scaler.
The tank is now ready for siting. Choose the position with some care as once the tank is set up it should not be moved. An perfect position would be near a window facing south, the quantity of sunlight falling on to the tank could then be controlled by blinds or by shading with curtains, but if such a position isn't accessible, then attempt to website the tank where the rays of the sun will fall on to the tank for a period during the day. It might well occur that it's impossible to satisfy either of these suggestions If this is so, then artificial light will need to be relied upon.