Glass and silicone for aquariums
The construction materials of the aquarium. The quality of the glass and silicone determines the safety and durability of the aquarium over time.
Detailed explanation
The glass in aquariums is standard float glass (sodium-calcium). The thickness depends on the size of the aquarium: 6mm for aquariums up to 60 cm in length, 8mm up to 80 cm, 10mm up to 120 cm, 12mm and more for larger aquariums.
Extra-clear glass (optiwhite or diamant) has a very low iron content which eliminates the typical greenish shade of normal glass. It costs twice as much but the transparency and colour rendering are significantly superior. For high-end aquariums it is now the standard.
The silicone used to glue the panels must be specific for aquariums: pure acetic, without fungicides or additives. Bath silicones contain substances that are toxic to fish. The reference brands are Dow Corning 795 and Ottoseal S 72.
Silicone life is 10-15 years under normal conditions. Over time it loses elasticity, turns yellow and may begin to release. An old aquarium with deteriorated silicone must be repaired or replaced before it fails.
Tempered glass should never be used for aquariums. If it breaks it explodes into a thousand pieces, releasing hundreds of litres of water in a few seconds. Normal float glass cracks slowly giving time for action.
Plexiglass (acrylic) is an alternative to glass. It is lighter, more transparent and more resistant to impacts. However, it scratches easily and yellows over time. High quality acrylic aquariums (such as Elos or Red Sea) use greater thicknesses and cell-cast acrylic.
The position of the aquarium is critical. The furniture must be perfectly level and able to support the weight (one litre of water weighs one kilo, plus sand, rocks and equipment). A 200-litre aquarium set up easily weighs 280-300 kg.