Aquarium Tank Bracing and Glass Thickness Guide

Glass thickness and bracing decide whether a tank holds its shape under hydrostatic pressure or bows outward over time. This aquarium tank bracing glass thickness guide from Gensou Aquascaping in Singapore lays out the practical thickness chart by tank length, explains the eurobrace and centre brace options, and covers the rimless calculations that aquascapers obsess over. Get this wrong and the tank fails. Get it right and it lasts thirty years.

Quick Facts

• 60cm length: 6mm glass adequate, 8mm common for rimless
• 90cm length: 8mm minimum, 10mm preferred for rimless
• 120cm length: 10mm minimum, 12mm safer rimless
• 150cm and above: 12 to 15mm depending on height
• Centre brace reduces required thickness by one step
• Eurobrace is a 5cm perimeter glass band on top, stronger than centre brace
• Rimless tanks rely entirely on glass thickness

Why Thickness Matters

Water exerts pressure proportional to depth. A 50cm tall tank pushes outward with about 0.05kg per square centimetre at the bottom seam. Across a 120cm front pane that is several hundred kilograms of force trying to bow the glass outward. Glass deflects under load. Too thin and the deflection cracks the silicone seam at the corners, or worse, the glass itself fatigues and shatters. Too thick adds weight, cost and visual clutter.

The Practical Thickness Chart

For braced tanks with a plastic rim or eurobrace, 60cm tanks use 6mm float glass. 90cm uses 8mm. 120cm uses 10mm. 150cm uses 12mm. 180cm and above moves to 15mm or thicker. These are starting points for tanks 50cm tall or less. Add one thickness step for tanks taller than 60cm. A 120cm tank that is 70cm tall should use 12mm rather than 10mm.

Rimless tanks remove the bracing safety margin entirely. Step up by at least one thickness from the braced numbers. A rimless 90cm should sit on 10mm rather than 8mm, especially in low-iron glass which is slightly less stiff than standard float.

Eurobrace Construction

A eurobrace is a continuous 5 to 8cm wide glass band siliconed around the entire top perimeter of the tank, like a picture frame inside the rim. It ties all four panes together and resists bowing along the full length. Most premium rimless tanks built locally for the 120cm and above range use eurobrace because it allows the front pane to remain unbroken by a centre crossbar.

The eurobrace also provides a useful ledge for hanging filter intakes and a partial cover against jumpers, though it is not a full lid.

Centre Brace

The centre brace is a single glass crossbar siliconed across the top from front to back at the midpoint of long tanks. It is cheaper to fabricate than a eurobrace and reduces required glass thickness by one step. The downsides are visual: it interrupts the top-down view, blocks light into the centre of the tank, and prevents using a single sheet of glass cover. Many older Singapore-built tanks from the 1990s and 2000s use this design.

Rimless Considerations

Rimless aquascapes have become the dominant style in Singapore over the last decade, especially for 60 to 90cm display tanks. Going rimless means relying entirely on the glass thickness and the corner silicone seams to resist bowing. Build with one thickness step above the braced equivalent, and inspect the seams every six months for stress cracks at the corners. Polished and chamfered edges look better but slightly weaken the glass at the chamfer; not a problem at sensible thicknesses but worth knowing.

Glass Type Choices

Standard float glass is fine for the vast majority of aquariums and is the default at most Singapore fabricators. Low-iron glass costs roughly 50 to 80 percent more and offers visibly clearer optics with no green tint, which is the aquascaping standard for display tanks. Tempered glass is much stronger but cannot be drilled after tempering, so plan plumbing holes before ordering.

Local Fabrication Notes

Singapore tank fabricators in Pasir Ris and Sungei Kadut work to these thickness standards as a matter of course. When ordering custom, specify the glass thickness, the bracing type, and whether you want polished edges. Expect to pay 30 to 50 percent more for low-iron in any given size. Custom 120cm rimless low-iron tanks run roughly $400 to $700 depending on height and edge finish.

Signs Your Tank Is Underbuilt

Visible bowing in the front pane when full, especially if you sight along the glass at eye level. Stress cracks radiating from corner seams. Silicone bead pulling away from the glass at the top. Any of these means draining the tank below the suspect area immediately and consulting a fabricator. Catching the problem early often allows reseal rather than replacement.

Related Reading

How to Choose Aquarium Glass Thickness
Tempered vs Low Iron Glass Aquarium
Acrylic vs Glass Aquarium Comparison
Aquarium Stand Weight Guide
Aquarium Tank Stand DIY Build Guide