How To Build An Aquarium - DIY Fish Tank - Help Guides - Swell UK

Why should I build my own aquarium?

A DIY aquarium is a rewarding project for anyone who wants a truly unique tank. It allows you the freedom to tailor every detail, from the dimensions through to the design, and perfectly compliment your space and style. For experienced fishkeepers, it also provides the opportunity to deepen your understanding of aquarium construction.

Tip: A well constructed tank must be watertight, structurally sound, and built with materials that are strong enough to hold a large amount of water.

Understanding aquarium construction

Aquariums may look like a simple design, but the craftsmanship is surprisingly complex. A pre-built tank has smooth glass edges, neat silicone seams, and precise corners. Some also feature trims or frames that add strength and help to distribute the weight of the water evenly. Larger tanks often use additional bars across the top to prevent bowing under pressure. These details are very important when building your own aquarium. Even a slight misalignment or uneven seal can lead to structural stress and damage.

Tip: Examine a pre-built aquarium before starting your project. Checking the details such as corners, silicone seals, and frames will give you a clearer idea of the quality you're looking to achieve.

Choosing the right glass

It's important to choose the right glass as it determines how safe and visually appealing your tank will be. Most tanks are constructed with float glass, whereas low iron glass (also known as OptiWhite) provides superior clarity and less of a green tint. Each pane of glass should be precisely cut, and the edges should be polished to prevent injury and ensure secure seams.

Aquariums are typically built in one of the following ways:

• Standard base: where all side panels sit on top of the bottom pane
• Floating base: where all side panels are fitted around the base.

The floating base method does provide a sleeker finish, although this method is typically harder to execute. Whichever design you choose, be sure to always use aquarium-safe silicone. Household sealants can release chemicals that are toxic to aquatic life.

For glass thickness, we recommend small tanks under 100 litres can use 6mm glass, whereas larger builds require 10mm or thicker panels.

Tip: When arranging your glass, allow a small gap of 1-2mm for silicone thickness between panels. This allows for a strong, flexible seal that won't crack under pressure.

Planning your aquarium dimensions

Before you start cutting your glass, take time to plan the dimensions carefully. Calculate the internal volume by multiplying the length, width, and depth, and consider how much weight that amount of water will be. Even a small aquarium can weigh a lot more than expected when filled.

It's important to choose a level and sturdy surface to support the tank one built. Uneven pressure can cause the glass to crack over time. Large tanks may require thicker glass and additional bracing, which will increase the cost of your project.

Tip: Use our Aquarium Volume Calculator to double check the measurements.

Braced vs braceless fish tanks

Braced tanks utilise horizontal bars or frames to strengthen the structure, which aids with preventing bowing, perfect for larger aquariums. However braceless tanks offer a sleeker, frameless look, but must be constructed using thicker glass to handle the water pressure safely.

Precision is essential for both designs. A small 1-2mm difference between the panels must not be overlooked, as it can cause gaps or misalignment that compromises the structural integrity of the entire build.

Tip: If this is your first time building an aquarium from scratch, start small and consider using a braced design. It's far more forgiving and easier to seal.

Building your own tank: Step by step

1. Preparing your materials: make sure all the glass panels are clean, dry, and dust-free
2. Apply aquarium-safe silicone: use masking tape to guide your lines and keep the silicone neat
3. Assemble the panels: starting with the base, attach the sides one by one, securing them as you go
4. Smooth the seals: run a gloved finger or silicone tool along the seam to ensure an even bond
5. Allow to cure: leave for at least 48-72 hours for the silicone to fully harden
6. Test with water: fill the tank in a safe area, like a garden, and check for any leaks before use

Neat silicone work takes a lot of practice, it's the hardest part of tank building. Even a tiny gap can compromise the entire build.

Check out our aquarium safe silicone range for the perfect seal on your tank.

Tip: If your silicone work looks uneven, don't panic. Let it fully cure, then cut away the messy sections with a blade and neatly reseal.

Common issues to avoid

DIY aquariums can go wrong for several reasons, here are the most common ones to avoid:

• Using the wrong sealant: be sure to use aquarium safe silicone, rather than a household sealant
• Cutting glass inaccurately: make sure to measure correctly and precisely before cutting
• Not allowing enough curing time: aquarium silicone requires a minimum curing time of 48-72 hours
• Skipping bracing large tanks: it's important not to skip this step if you desire a large tank for maximum safety

A small leak can cause major damage to your home, so patience and precision are key. Always test your aquarium thoroughly before introducing fish.

Tip: Keep silicone on hand for emergency repairs. If you notice persistent leaks, it's safer to rebuild the tank from scratch.

When buying a tank might be a better option

Although building your own aquarium can be a fun project, most hobbyists buy a pre-made tank as it is safer, quicker, and cheaper. Manufactured aquariums are built with professional grade aquarium safe sealants, and are pressure tested beforehand. Shop-bought tanks often come with a warranty for peace of mind. They may even include purpose built cabinets, lids, and filtration options that homemade tanks don't.

If you're new to the hobby, or have little to no DIY experience, a pre-built aquarium is usually a better choice.

At Swell UK, we have an extensive range of pre-built aquariums, so you'll be sure to find the right tank for your space. Check out our aquariums today.