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How to Design an Aquarium
Building your own DIY aquarium is fun and easy. Designing a custom glass aquarium is pretty straight forward. It is just a matter of selecting the size of the aquarium, the glass thickness to be used, then put it all together. It sounds simple, right? In reality, it really isn't that difficult. Just follow the steps, one at a time, and you will be surprised at how easy it really is.
Determine the "footprint" (front to back, side to side measurement) of the tank. To a great extent,... the footprint will be determined by the final location of the tank and the stand that it will rest upon.
Make a note of the tank footprint measurements.
In order to determine the size of the side glass panels, you will first need to determine the thickness of the glass you will be using. (See the Glass Placement graphic ). Note that the side pieces are set inside the front and back panels.
For this discussion, we will be using single strength glass, as opposed to tempered or "safety" glass. Single strength glass is what you see in most aquariums the windows in your house. It can be cut to whatever size you wish and the sharp edges can be ground smooth to avoid injuries.
Refer to the Aquarium Glass Thickness Calculator to help you determine the glass thickness to use for your aquarium.
When a glass aquarium fails, it is normally for one of 2 reasons:
- The adhesive (usually silicone) used to bond the glass panels together fails to adhere to one or more of the glass panels.
- The structural integrity of the glass is destroyed (it breaks).
Adhesive bonding failure is fairly easy to prevent:
- Use the appropriate high quality silicone.
- Clean the bonding surfaces with acetone before applying the silicone.
- Fit the glass panels together with a minimum gap between the panels (essentially glass-to-glass contact).
- Assemble the glass panels promptly after applying the silicone.
When a glass panel in an aquarium fails (breaks) it is normally from one or more of several causes:
- Impact from a foreign object.
- A scratch or chip reduces the strength of the glass.
- The top of the glass panel bends beyond its breaking point.
Prevention of the first 2 causes is pretty simple: Avoid striking the tank and don't scratch or chip it. Preventing glass in an aquarium from bending to the breaking point is pretty simple, too.
The glass at the bottom and sides of the aquarium can't bend if the silicone adheres to the glass. The normal place for aquarium glass to bend is at the top edges of the front and back panels. The thicker the glass is, the more pressure it can take without bending, or you can simply brace the top edges to keep them from bending.
Many of the manufactured glass aquariums you see on the market employ plastic or metal bracing around the top of the tank as well as a piece across the center. This allows them to use a thinner (read: cheaper) glass and also provide a bracket to hold glass canopies. Many of the manufacturers will also use angle plastic or metal along the bottom and sides. This can be for cosmetic effect (looks) or to help hold the joints together.
Back to selecting the right glass thickness for your new tank.Continue to 2 of 2 below.
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Selecting the Right Glass Thickness
If you look at the Aquarium Glass Thickness Calculator a "Safety Factor" is displayed in each box. To explain this Safety Factor, from Warren Stilwell's Glass Thickness Article on the Federation of New Zealand Aquatic Societies web site:
"The variability of the strength of glass due to limitations of the manufacturing process means a suitable safety factor must be used when calculating glass thickness. The factor commonly used is 3.8. While not a perfect guarantee, it will remove... all risk bar that of damaged or very poor quality glass. The main damage that will cause failures is scratches and chips. Also a point load on the glass surface will cause it to fail. For this reason a soft packer like polystyrene is used under aquariums to stop the point loading of dirt and grit.
Also when manufacturing an aquarium, the joining compound (commonly silicone) must have a minimum thickness (0.5-1mm) to allow for irregularities along the glass edge. When glass is cut it is not flat along its edge unless it has been specially ground.
It is possible to use a lower safety factor if the glass is of excellent quality and has no internal stress. It is at the designer's risk however to lower the safety factor."
How to Maintain an Acceptable Safety Factor With Thinner Glass
If you want to use a thinner glass to keep your costs down and still maintain an acceptable Safety Factor, you can simply design your tank as if it were 2 tanks by installing a front-to-back brace across the top/center of the tank. This effectively turns a 4' long tank into 2 2' long tanks.
To demonstrate this idea, look at the 21" high, 4' wide tank line in the Calculator. It indicates that using 9mm glass will give you a Safety Factor of 2.92. However, if you use a front to back brace, structurally turning the tank into 2 2' wide tanks, it increases the Safety Factor to 4.1, which is a very satisfactory Safety Factor. If the side panels are no more than 2', they will also have a Safety Factor of 4.1.
If you want to have a flat topped tank, you can install (silicone) the brace between the front and back panels, level with the top of the tank. How wide should the brace be? 3" would be a good width, but if you are going to install a glass canopy on the tank, adjust the brace width to accommodate the canopy. If you want more strength in the center of the tank, you can use 2 narrower braces siliconed together.
Determining the Width of the Side Glass Panels
Once you have determined the thickness of the glass you will be using for the front and back panels, calculating the width of the side panels is simple. Double the width of the glass and subtract that number from the front to back measurement of the bottom panel. Example: If the front-to-back measurement of the bottom panel is 18" and you are using 1/4" glass, your side panel width would be 17 1/2".