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Fish Tank Glass Thickness Guide: What You Need To Know

Fish tanks are beautiful. Whether they’re large tanks in the public aquariums or small aquariums in your neighbor’s living room, fish tanks always stand out. But have you ever wondered how its glass withstands the pressure of the water? There are many answers to this question, but generally, the answer lies in the glass’s thickness!

A fish tank’s glass thickness is calculated based on the tank’s water volume and the glass safety factor. Experts recommend using a safety factor of 3.8 when calculating a suitable glass thickness. You can measure the ideal thickness with online calculators, a MIG laser gauge, or vernier calipers.

In this article, you’ll learn about the correct glass thickness for different size fish tanks and understand how to measure and calculate the right thickness based on an acceptable safety factor.

What Is the Perfect Fish Tank Glass Thickness?

fish tank glass thickness guide
Water is heavy. One gallon (3.9 liters) of water weighs a whopping 10 pounds (4.5 kilograms). It’s, therefore, vital to ensure that the glass you use is strong enough to withstand this weight.

What Is the Best Glass for an Aquarium?

The best glass choice for an aquarium in the market is annealed glass (also known as ‘plate’ glass). Annealed glass is not easily shattered and can be repaired when it is broken, which makes it the perfect choice for a fish tank. Laminated glass, toughened glass, and polycarbonate plastic are also good options.

For a robust and durable fish tank, experts advise people to avoid tempered glass. Tempered glass doesn’t hold and is likely to be shattered entirely from a small crack. Therefore it doesn’t guarantee a safe home for your fish.

Acrylic Vs Glass Aquarium: Which One Is Better?

The quality of glass also depends on the manufacturer. The tensile strength varies from 19.3 to 28.4 megapascals depending on how the glass was produced. Because of this, a safety factor of 3.8 is used to measure the thickness of the glass.

According to Warren Stilwell, the safety factor accounts for the glass variability in the manufacturing process. He further notes that the joining compound used when building an aquarium should be at least 0.5 to 1 mm (0.02 to 0.039 in) thick to cover any irregularities on the glass edges.

Although this factor isn’t an absolute safety guarantee, it reduces the risk of glass failure brought about by damaged or poor-quality glass.

What Does Aquarium Glass Thickness Mean, and Does It Matter?

Generally, glass is brittle and cannot deform like other metals. It bends to a certain degree and then breaks. Aquarium glass thickness refers to the thickness of the glass plate.

When building an aquarium, glass thickness is significant. This thickness determines if the glass will withstand the water pressure depending on the depth of the aquarium. In other words, can it keep the water from breaking and shattering the glass?

To build a successful aquarium, the glass thickness should withstand the water pressure inside the aquarium.

How Do I Measure the Fish Tank Glass Thickness?

fish tank glass thickness guide
If you already know your aquarium’s perimeter measurements (the length, the width, and the height), the next step is to find out the perfect glass thickness based on the safety factor.

Here are some ways and tools that you can use.

Online Calculator

You can find a standard thickness calculator online. All you need to do is input the aquarium measurements plus the safety factor, and it’ll calculate the thickness you need. If your aquarium measurements are exact, the calculator should give you the thickness required for the fish tank.

Glass Thickness Measurements Apps

There are a ton of downloadable glass measurements apps that you can use. But you only need to choose one with good reviews and use it to estimate your aquarium glass thickness. To use these apps, you need to have the correct perimeter measurements of the tank.

They might not be very accurate, but they are worth a try. Input the correct tank measurements together with the safety factor, and the app should be able to calculate the required thickness.

Calculate Manually

It’s possible to get your calculator to calculate the thickness required manually. You just need to know the fish tank measurements and safety factors, and you can use the formula illustrated in the next section to come up with an estimated thickness.

Unfortunately, this method is prone to errors. Even if you have the exact measurements, it’s not likely going to get the correct thickness.

Fish Tank Glass Thickness Chart

The chart below shows some general calculations or guides that can help you determine how thick aquarium glass should be. The top row shows the tank’s length, and the column on the left shows the tank’s height.

fish tank glass thickness guide

This chart shows some general calculations or guides that can help you determine how thick an aquarium glass should be. The top row shows the tank’s length, and the column on the left shows the tank’s height.

The glass thickness is shown in millimeters (mm), with the number in the parentheses indicating the safety factor. Always aim for a thickness that has a safety factor of 3.8 or greater.

Can You Maintain a Safety Factor With Thin Glass?

The truth is, it’s better safe than sorry. Hence, it’s always safer to use the recommended glass thickness for your aquarium size to avoid future accidents. But if you want to save a buck and go with thinner glass, here’s a tip on how you can increase your thin glass aquarium’s safety factor when using a thinner glass.

The trick is to split your tank and design it like it were two tanks. All you need to do is install a brace that splits the tank into two equal parts. For example, you can turn a 6-foot (1.83-meter) tank into two 3-foot (0.91-meter) tanks by supporting the from and back glass panels.

This ‘brace support’ adds to the glass’s safety and lowers the likelihood of damage and breakage. For example, from the chart above, a 9mm glass gives you a safety factor of 2.82. If you split the tanks and structurally turn them into two 3-foot tanks, the 9mm glass will have a safety factor of 4.01 for each tank. That automatically makes the tank stronger and safer.

Tips To Prevent Fish Tank Glass Failure and Damage

fish tank glass thickness guide
The thought of the fish tank breaking can be terrifying. Minor damage or leak on the tank can potentially lead to many problems that might include the death of your precious fish. But what causes fish tank failure?

These are the main reasons why your new and perfect aquarium might fail. Below are some of the causes and how to avoid them.

Unfavorable Safety Factor

When an aquarium is made without putting the glass safety factor into consideration, it’s a disaster waiting to happen.

It might look safe and beautiful for a few days as the glass expands and tries to accommodate the water’s weight. But the glass is likely to shatter once it has reached its limit. Ensure to follow all the safety measures when you’re purchasing glass to build your aquarium.

Poor Manufacturing

If not carefully sealed, the silicon used to bond the glass might fail to bond on one or more sides of the glass. The glass panels will then tug or pull on the other, causing a leak or even breaking the aquarium. To avoid this, you must ensure to:

  • Use high-quality silicon
  • Thoroughly clean the glass surface with acetone before bonding.
  • Ensure that there a minimum thickness of 0.5 to 1mm of silicon between the panels
  • To avoid shifting of glass, tape the glass edges together with tape when the silicon is drying.

Uneven Base or Poor Base Support

Uneven base and poor base support are the most common causes of any failures in high-quality aquariums. If the tank’s base isn’t supported on a flat surface, it’ll lead to weight being shifted to one side and causing uneven pressure, leading to cracking or breaking of the glass. To avoid this, always ensure that the tank is placed on a surface that doesn’t leave it tilted.

External Factors

The glass can also fail due to external factors such as the impact of foreign objects. You can avoid this by keeping the fish tank away from areas with these hazards. Primarily ensure that the tank isn’t in a busy area and not very close to the kid’s play area.

Can a Broken Fish Tank Be Repaired?

cracked fish tank
Finding a crack or a leak on your fish tank can be exhausting. Sometimes, you don’t notice the crack until it’s too late, and by that time, the damage is too severe. But cracks in glass fish tanks are more common than you think. So, don’t stress. There is a solution.

Repairing a fish tank glass crack is as easy as a walk in the park. With the right tools and materials, you do not need to call an expert. You can do it yourself, and it can be a fun project.

How To Repair a Leaking Glass Fish Tank?

The trick is to repair it as soon as you notice the crack. This is especially important if you have a big fish tank. Leaving it unrepaired will lead to even more problems. The water pressure inside will continue to press on the crack, which will continue to get bigger and eventually make the aquarium shatter into pieces.

Depending on where the damage is located, you first need to either move the fish and empty the aquarium or drain water until the water level is below the damaged area. After the damaged area is free to be repaired, follow the below steps to repair the crack.

#Step-1: Use a Razor Blade Scraper to Remove Old Sealant

If the crack is on the area that was sealed, use a razor blade scraper to remove the old sealant. Remove the silicon on the area that needs repair only.

Ensure that you remove all the old adhesive from the area, as sometimes, the old sealant doesn’t bond well with the new sealant. Be very careful not to drop any pieces into the water if you didn’t empty the tank.

#Step-2: Clean the Surface With an Acetone-Soaked Towel

After you have prepared the surface, clean it properly using a towel soaked in acetone. Wipe until there’s no foreign material or debris left, dry the area, and give it 15 minutes to completely dry. Thoroughly cleaning the surface ensures that the sealant works on a clean surface free of impurities that could prevent proper bonding.

#Step-3: Apply the Adhesive With a 100% Nontoxic Sealant

Using a 100% nontoxic silicone sealant, apply the adhesive on the cracked/cleaned area. A caulking gun will come in handy when applying the adhesive. You can buy the caulking gun at a hardware store. Ensure that you spread the silicone on the cracked area using a caulking tool or a damp finger to cover up the crack thoroughly.

You must guarantee that there’s absolutely no fungicide or any other impurities in the silicone that could affect the fishes’ health. It should be 100% non-toxic.

It’s much more efficient to seal the crack from the inside of the tank than the outside. This is because the pressure from the water will work to your advantage to tighten up the seal.

#Step-4: Allow the Sealant 24 Hours to Dry

The sealant will need at least 24 hours to dry completely. But the recommended time is 24 hours, as this will ensure that the silicone has dried and settled correctly. You can also use a drying lamp that’s not more than 110°F (43°C).
Inspect the Seal Before Refilling It With Water
Before you restore your fish tank, inspect the repair to ensure that everything is nicely sealed and dried up. Ensure that there are no more cracks or leaks that you missed. You can fill up the tank and wait a few hours to monitor the situation.

#Step-5: Restore Your Aquarium; Tidy It Up

After confirming that everything is nicely sealed, it’s now time to restore your aquarium. Take this chance to clean and tidy up a bit. You can also add some chemicals or plants for fishes’ nutrients. Then carefully place your fishes back into their home.

All You Need To Know To Build a Fish Tank DIY

fish tank glass thickness guide
Now that you have the information on the thickness required for a fish tank, let’s find out what you need to build a small or medium-sized fish tank DIY. Building an aquarium can be a fun family activity. But it can also be quite challenging and need high-level attention and care.

The first step into building an aquarium is to decide whether you want a saltwater aquarium, a high-end reef tank, or a simple freshwater aquarium. This will help you know what kind of material you need, as each type requires a specific type of material and care.

It’ll help you determine the thickness of the glass needed, the decorations of algae that will be put in, the level of care needed, etc.

Gather Supplies (Silicone, Gun Dispenser, Etc.)

The quantities will depend on the size of the aquarium you’re building, but here are the materials needed for this project:

Prepare the Tank Before You Start Cutting

Glass is an essential item when building an aquarium. Hence, you should choose carefully and make the right choice depending on the size of your aquarium.

For small fish tanks (e.g., 20-gallon or 75.71-liter freshwater tanks), ordinary plexiglass with the right thickness is a great option. But for bigger tanks, annealed glass or toughened glass is recommended because they’re thick enough to stand huge pressure. These two also don’t scratch easily and don’t require a lot of maintenance.

Here are tips to follow when preparing your glass.

  • Draw a good schematic before you start cutting the glass to ensure that it’s a perfect fit.
  • If you have any doubts, get a professional glazier to cut and prepare the glass for you. The cut needs to be perfect so that the glass fits perfectly to avoid any leaks.Pick the cover for your aquarium and prepare it beforehand. It’s not a good idea to use glass as a cover, as it’ll hinder oxygen flow.

How To Build a DIY Fish Tank

With all the preparations done, it’s now time to start building your tank:

  1. On a clean surface, neatly arrange all the tank walls by placing the base in the center and walls on each side of the base.
  2. Use sandpaper to polish the edges of the glass for any irregularities.
  3. Use the towel dipped in acetone to thoroughly clean the class, especially on the edges where the glass will connect. There’s a risk of the glass not bonding if there’s any foreign material on the surface.
  4. Place the duct take on the top of the edges to prevent silicone from sticking on the glass.
    This will also help you apply the silicon more accurately.
  5. Once you’ve finished sticking them together, give the silicone some time to rest and dry. This will depend on each silicone manufacturer, so check the packaging for the recommended time.
  6. Now use the gun dispenser to start applying silicone and sticking one piece at a time – laying it on all the pieces at once will lead to uneven drying of the silicone.

Note: Ensure that you carefully attach all the sides using the same technique and that everything is nice and tight and the edges don’t slide off. You may put more duct tape between the edges to keep them in place. If there’s any spill-off, use the scraper to get it off the glass.

Once you’ve let your fish tank sit for at least 24 hours, it’s ready for use. But it doesn’t hurt to check and make any final adjustments if needed.

5 Valuable Tips for Setting Up a Fish Tank

fish tank glass thickness guide
Now that you already have your fish tank in place, here are tips to help you have a successful fish-keeping hobby:

#Tips-1: Water Balance Is Essential for the Fish To Survive

An aquarium is a living system. As such, the conditions must be favorable for inhabitants to be able to survive and thrive. A freshwater aquarium takes a lot of time and effort to attain a good balance. Test your water for ammonia and nitrite before you add our fish.

To ensure that the water has optimal water chemistry to allow your fish to thrive, introduce a few fish first and observe them for a few days before adding more. This will give the essential bacteria that help with water balance time to grow. Add more fish after you’ve confirmed that the water ammonia and nitrate are at zero.

#Tips-2: Decorate Your Aquarium To Make Your Fish Feel at Home

When decorating your fish tank, your focus should be on the fish. You need to decorate in a way that will make the fish feel at home and comfortable. Some species like a lot of covers, while some like a lot of open space to allow them to swim around.

Hence, it’s essential to do your research on the type of fish you’ll keep and keep their preferences in mind when decorating. Remember to give each fish space to claim as their home if you have more than one species.

#Tips-3: The Fish Tank Lighting Should Be Favorable to the Fish

Allow your fish to have a downtime and rest from all the pop and glam. The fish tank should have a day and night cycle switch timed to turn off the lighting and give the fish time to rest. If your fish tank doesn’t have a timer, you can get one from the hardware or pet store.

#Tips-4: Don’t Clean the Aquarium for the First Few Weeks

You’ll need to clean the aquarium regularly, but the first few weeks are essential for the bacteria to settle and build water balance. In these weeks, don’t disturb the aquarium and allow the bacteria to settle. You can clean the aquarium regularly after the first few weeks.

#Tips-5: Do Thorough Research Before You Buy Your Fish

Before you purchase your fish, do proper research. Different species of fish have different characteristics and preferences. For example, schooling fish are the happiest in groups. They do well when they’re in batches of 5 or more. Some species prefer to be in pairs, trios, or even by themselves.

You also need to understand what their food preferences are. I’m sure you want your pet to be well-fed and happy. So when you meet your local aquarium expert, remember to ask all these questions.

How To Maintain and Take Care of Your Fish Tank?

fish tank
Caring for your fish tank can be a whole different guide. But in this article, let’s mention a few tips and tricks to help you keep a safe and tidy place for your pet.

Maintaining a fish tank doesn’t require too much time and effort, but it does require your utmost attention and care.

  • Water conditioning. It’s not safe to directly feed water from your tap to your aquarium. The water needs to be treated and conditioned first to balance the pH and eliminate chlorine before putting it into the aquarium. You can do this by using basic water conditioning formulas.
  • Temperature maintenance. Fish are susceptible to the water temperature. Hence, monitoring the temperature of the tank is very important. Consider installing a temperature maintaining device onto your fish tank to keep the temperatures under control.
  • Replenish water minerals. The minerals and nutrients in the water will diminish with time. These are important to the fish and need to be replenished often to ensure they’re healthy and safe.
  • Filtration. The fish tank’s water needs to go through constant filtration to ensure that it’s safe and healthy. You need to check the filter often to ensure that it’s working correctly. Clean the tank frequently to guarantee that dirt and debris don’t float around and harm the fish.


So there you have it. I hope we’ve answered your question. The fish tank glass thickness is what ensures that your fish tank is both strong and durable. Therefore, it’s vital to ensure that you use the correct glass thickness when building a fish tank.

There are many ways to calculate the required ultimate glass thickness for your tank. You just need to know the tank’s measurements and use the safety factor of 3.8 to calculate the perfect thickness that’ll effortlessly sustain the water’s weight.

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