Tempered vs. Plate
Glass fish tanks are the most popular in the hobby today. Glass aquariums are built with either tempered or plate glass. Tempered glass is glass that is heated super hot and then cooled quickly resulting in super strong, lightweight glass. Tempered glass tanks will tend to shatter into many pieces rather than just crack when broken. Most glass fish tanks have a minimum of a tempered glass bottom with the four sides being plate glass. Note: It is highly suggested not to drill a tempered glass tank. There are some out there that try, but most end up with shattered tanks.
Plate glass is thicker, a bit heavier, and will tend to crack at the point of impact rather than shatter like the tempered glass. Plate glass is more common in the beginner and smaller aquariums. I prefer to have tropical fish tanks with a minimum of a tempered bottom. Many experienced fish keepers drill plate glass tanks and have success when performed correctly with the appropriate tools. Drilling tanks is more often performed in marine tanks for overflows and sump filtration, a lot of which is not needed for freshwater tropical fish keeping.
When you purchase your aquarium, most glass fish tanks will have a sticker on the frame or exterior bottom of the tank stating either plate or tempered glass.
Glass tanks tend to offer a clearer view of the fish inside due to nearly all glass aquariums are flat sheets of glass. When you see bow front or hexagon shaped tanks, some views are distorted due to the shape of the acrylic or glass. I must add that even though the view is clearer, glass aquariums tend to have a green or bluish tint to them.
Look at the corner of the tank where the plates of glass meet, you will notice the hint of color that I am talking about. There is a type of glass called Starphire that offers the same benefits of normal glass but without the color tint.The view is nearly perfectly clear. The picture on the right illustrates the clarity of starphire glass tanks. Notice how clear the pane of glass is on the right. That is starphire glass.
Glass fish tanks may not be for you if you are shopping for an odd shaped tank. The reason is that most glass aquariums are simply rectangular due to the fact that glass is much more difficult manipulate.
If you select a glass fish tank, ensure you have a hood or canopy on it to help control the temperature of the water. Aquariums made of glass are not well insulated when compared to acrylic tanks. Glass tanks tend to lose heat easier therefore you should have a adequate heater and hood on your tank.
Advantages of Glass Tanks
-Does not scratch as easy as acrylic
-Cheaper, not as expensive as acrylic
-Easily available: Rather easy to find in most pet or fish stores
Disadvantages of Glass Tanks
-Heavier: Consider the strength of the stand and floor on which the tank will rest.
-Limited Shape Design: Pretty much rectangular due to the lack of manipulation in glass sheets.
-Glass tint: A slight blue-green tint to the glass.
-Loss of heat: Not as insulated as acrylic.