9 Best Aquarium Silicone to Fix Leaks With

Aquarium silicone adhesive/sealant is a silica-based water-resistant polymer that replaces toxic waterproof adhesives for its inertness and elasticity in water. However, not every silicone sealant is safe for aquariums. Sealants with anti-molding agents may leech into the water and contaminate the tank.

Silicone sealants are mostly used to build fish tanks and repair leaks, but you may also use them as underwater adhesives to create caves, anchor plants, and join rocks together. Moreover, as most of the sealants can cure underwater, you don’t need to wait multiple days before filling up your tank. 

In this article, we’ll go through 9 such aquarium-safe silicone sealants that you can use for a wide range of applications.

9 Best Aquarium Silicone

1. Aqueon Aquarium Silicone Sealant

 

Available in 10-ounce standard caulking cartridge packs, the Aqueon Aquarium Silicone Sealant is a premium transparent silicone sealant that stays flexible even after curing and months of usage. It’s also available in black and is quite a value for money if you’re considering high-quality options. It also has a relatively longer shelf life if you follow the manufacturer’s instructions.   

Key Features

The permanent flexibility promise of Aqueon ensures that the bondings don’t crack or shrink during the water temperature changes in the tank. In our experience, glass-to-glass bonding stays strong for many years. 

Absolutely aquarium-safe, 100% non-toxic silicone is used to produce the products. It doesn’t contain any non-molding agents or have oxime content in it.

• For Both Freshwater and Saltwater Aquariums

This product can be used for both saltwater and freshwater aquariums. The stable silicone doesn’t allow saltwater to corrode the bonding.

While you may find 24 hours to be adequate, In our experience, 48 hours is required for this sealant to reach the maximum strength. 

Pros

• Effective sealing to maintain freshness
• Works similarly well for acrylic tanks.

Cons

• The odor is a bit too strong. Work in a well-ventilated area. 

Remarks

Aqueon Aquarium Silicone Sealant is one of the most premium options for saltwater and freshwater aquariums

2. SELSIL Aquarium Silicone Clear Sealant

 

Value for money and available in 10-ounce caulking cartridge packs, SELSIL Aquarium Silicone Clear Sealant is suitable for both saltwater and freshwater aquariums. It’s made from 100% silicone polymer and works pretty well on non-porous surfaces, including glass and acrylic. The product also stays pretty flexible to protect your aquarium from leaking and cracking. 

Key Features

• Doesn’t Contain Solvents

SELSIL clear solvent doesn’t contain harmful chemicals or solvents that often harm the microorganisms and fish in aquariums.

• Resistant to Ozone and UV

The product doesn’t lose elasticity when exposed to ozone and UV radiation, meaning it can be used for both indoor and outdoor aquarium applications. 

Although we’ve found it to be a bit longer, the product claims to have a 24-hour curing time before it can reach max strength. We recommend waiting for at least 48 hours for aquarium use.  

• Wide Application Temperature

It supports a wide application temperature range of 41 – 104 Fahrenheit or 5 – 40 Celcius. It should cure optimally within this temperature range. 

Pros

• The odor is relatively lower than other alternatives. 
• Cap design keeps it fresh for months. 

Cons

• Curing time could be a bit longer depending on the weather conditions

Remarks 

SELSIL Aquarium Silicone Clear Sealant is the best cost-effective aquarium silicone sealant.

3. ASI Clear Aquarium Silicone Sealant

 

Forming one of the best cohesive bonds to acrylic and glass, the ASI Clear Aquarium Silicone Sealant comes in 10.2-ounce plunger mechanism packaging with claims to withstand pressure from aquariums up to 750 gallons. It also doesn’t lose flexibility when exposed to UV for a long time—preventing cracks from being formed. 

Key Features

• Makes Strong Bond Without Primer

You don’t need to use a primer on the surface to use ASI silicone sealant. It’s designed to create strong waterproof bonds to glass and acrylic. It may also be used in vivariums and hydroponic systems. 

The product is made from 100% non-toxic silicone and doesn’t contain non-mold chemicals and solvents.

• Suitable for Both Saltwater and Freshwater Aquariums

ASI Clear is suitable for both saltwater and freshwater applications. It retains its characteristic elasticity and transparency even in saltwater aquariums.

• Wide Application and Operating Temperature

The product supports an application temperature range of 0-120F and an operating temperature range of -70 to 450F.

Pros

• Dries pretty fast and cures in less than 24 hours. 
• Pretty cost-effective compared to some products on this list. 

Cons

• The vinegary smell is quite intense and not safe for indoor application before curing. 

Remarks

ASI Clear Aquarium Silicone Sealant is the best transparent silicone for areas with major temperature deviations. 

4. Aquascape Black Silicone Sealant

No products found.

No products found.

 

Specially designed for pond liners and aquariums, Aquascape Silicone Sealant comes in 10.1 Oz caulking cartridges. The product has both black and clear variations for different application requirements, including repairing and building fish tanks. It also works in both saltwater and freshwater environments.    

Key Features

• Unique VOC Compliant Formula

The black dye formula used in the silicone is VOC-approved and shouldn’t harm your fish or other aquatic creatures. It also offers excellent adhesion to form strong bonds with acrylic and glass. 

• Can Withstand Extreme Temperatures

We couldn’t test it, but the product claims to withstand extreme temperatures between -40 to 200F. However, an outdoor temperature of 40 – 80 F cures silicone the best. 

• Allows Water Contact in 30 Minutes

The product allows water contact in about 30 minutes in optimum conditions. Our advice would be to wait at least 24 hours before water contact or the introduction of live fish. 

Owing to the VOC approval, the Aquascape Black Silicone is extremely UV tolerant and doesn’t break bonds or form cracks with long-term exposure. 

Pros

• Doesn’t smell any worse than other products. 
• Black color looks very natural in ponds. 

Cons

• The silicone is thicker than usual and refuses to come out of the tip without additional pressure. 

Remarks

Aquascape Black Silicone Sealant is the best black VOC-approved aquarium sealant.

Also Read: Aquascaping Styles For Aquariums 

5. AG Aquarium Silicone Sealant 

 

Cured through the release of acetic acid and suitable for building or repairing your aquarium, AG Aquarium Silicone is a transparent sealant packaged in 10.5 Oz caulking gun refills. Compared to other silicone sealants with acetoxy curing, AG is much more cost-effective and comes in a dry-proof sealed tube.   

Key Features

• No Additives or Fungicides

Made for aquariums and produced with 100% harmless silicone, AG Aquarium Silicone Sealant doesn’t contain solvents or fungicides. 

• Remains Flexible for Years

Similar to other premium options, this sealant also stays flexible for years to minimize the effects of stress and strain on the silicone bond.

• Safe to Touch After 2 Hours

Thanks to acetoxy curing, you can safely touch or expose water to the silicone seal only after 2 hours. However, allow it to cure for 24 hours before you can introduce fish and treated water.

• For Both Freshwater and Saltwater Aquariums

The product can be used for both saltwater and freshwater aquariums. The bonding is strong enough to sustain reef aquariums. 

Pros

• Acetoxy curing for stronger bonds and better waterproofing. 
• Dries up pretty quickly and reaches max strength in a day. 

Cons

• The odor is pretty strong. Better to leave it in well-ventilated areas to cure. 

Remarks

AG Aquarium Silicone Sealant is one of the most cost-effective fast-curing alternatives. 

6. Kraken Bond 100% Silicone Aquarium Safe Sealant

 

Available in clear and black options, Kraken Bond Silicone is made exclusively for aquariums and surfaces that may come in contact with water. Its 10-oz cartridge is designed to fit caulking guns and has the option to buy up to 12 packs at a discount for larger projects. Kraken Bond also offers a solvent and fungicide-free sealant with this product.

Key Features

The Kraken Bond Aquarium Sealant is made with 100% silicone and doesn’t contain any anti-mold agents or toxic elements that make it harmful to aquarium inhabitants. 

• Attachable to Most Decorations

This product makes strong bonds with most non-porous surfaces, such as glass, acrylic, and PVC, to help you create interesting structures. 

• Remains Flexible for years

The bonds remain flexible for years due to UV and ozone resistance. The flexibility helps minimize cracks and shrinks. 

Kraken Bond is acetoxy cured. This makes the process faster but releases a lot of acetic acid fumes that may cause discomfort. It almost cures after 24 hours and reaches maximum strength within 48 hours. 

Pros

• Suitable for both freshwater and saltwater aquariums
• Doesn’t contain solvent or fungicides

Cons

• Uncomfortable strong smell, probably due to acetic acid. 

Remarks

Kraken Bond 100% Silicone Aquarium Safe Sealant is the best black silicone with faster curing.  

7. ASI Black Aquarium Silicone Sealant 

 

Withstanding a high amount of stress and temperature range, ASI Aquarium Silicone Sealant comes in a 10.2-oz cartridge to use with caulking guns. This black sealant is mostly suited for turtle tanks and aquariums with black substrates but can be used in any type of freshwater and saltwater tank. Moreover, it has a high tensile strength and remains flexible for years. 

Key Features

RTV silicone sealants cure at room temperature and don’t require UV lights or heat sources to reach maximum strength. It’s better to leave ASI Black curing for a few days before introducing water and live creatures. 

• Wide Application and Operating Temperature

This sealant can be applied in surface temperatures between 0 to 120F and withstand temperatures from -70F to 450F. 

ASI Black can be applied in vertical joints without any issues tangential, like sagging or flowing. It helps create a more symmetrical joint when building aquariums. 

• Primerless Adhesion to Glass

Just cleaning the glass and removing any dirt is sufficient to use the sealant. You don’t need to use any primer before applying the silicone sealant to your aquarium. 

Pros

• 24-hour fast curing time, but needs to be dried for at least 2 days before the fumes go away. 
• Works similarly well on PVC and acrylic. 

Cons

• The smell is pretty strong and must be used in well-ventilated areas. 

Remarks

ASI Black Aquarium Silicone Sealant is the best black silicone for building aquariums in extreme weather.

Also Read: Nano Reef Tank Setup And Maintenance (Ultimate Guide)

8. Apel Aquarium 100% Silicone Sealant

 

Available in large 10.4Oz caulking gun cartridges, the Apel Aquarium Sealant is made exclusively for aquariums and vivariums. This transparent silicone sealant forms a pretty strong adhesion bond with glass, PVC, and acrylic. Although it lacks a black variant, you can get a pretty good discount by going for the bundled pack of two. 

Key Features

Apel Silicone Sealant doesn’t contain solvents or fungicides—making it suitable for aquarium and vivarium usage. It’s made from 100% non-contaminant silicone. 

• Remains Flexible for a Long Time

The product is UV resistant and will stay flexible for years to come to manage the stress caused by the expanding and shrinking surfaces with temperature changes.

With a drying time of 1-2 hours and a curing time of 24 hours, it’s one of the quickest-curing aquarium silicone sealants out there. However, we recommend waiting for at least 2 days to introduce water. 

• Wide Operating Temperature

Apel Silicone can withstand a surface temperature of -58 to 392F, which is enough in most areas with extreme climates.  

Pros

• Doesn’t smell as bad compared to other quick-curing solutions.
• UV resistant. Ambient light doesn’t harden the silicone seal.

Cons

• Expose to water only after 24 hours. It feels soft to the touch and leaks before that. 

Remarks

Apel Aquarium 100% Silicone Sealant is the best low-smelling aquarium silicone. 

9. Akfix 100AQ Aquarium Safe Silicone Sealant

 

With a bit smaller 9.5Oz caulking gun cartridge package of transparent silicone, Akfix 100AQ is designed to fulfill the needs of aquarium applications. It cures with atmospheric moisture and doesn’t need additional heat or UV radiation to cure faster. It also creates strong bonds with non-porous surfaces like glass, PVC, and acrylic.

Key Features

• 100% Solventless Silicone

Akfix is made of 100% solventless silicone absent of any fungicides. It’s harmless to fish or any other aquatic creatures. 

The putrid smell that you may experience during drying comes from the acetic acid released through the acetoxy curing system. It makes the curing process faster and more homogenous. 

• Wide Application and Operational Temperature

With an operational temperature resistance of -58 to 392F and application temperature of 40 to 104F, Akfix 100AQ has one of the widest temperature ranges in this segment. 

• Remains Elastic for a Long Time

Owing to the UV and other chemical resistances, 100AQ remains elastic for a long time—surviving stress and strain caused by temperature changes. 

Pros

• Resistant to UV and many other chemicals. Doesn’t allow aquarium water or lighting to degrade the seal. 
• Rapid curing. Feels hard to touch after 2 hours. Curing takes 24-48 hours.
• For freshwater and saltwater both. 

Cons

• The smell of acetic acid may cause burning in the eyes and discomfort. Keep your projects outside or in a well-ventilated area. 

Remarks

Akfix 100AQ Aquarium Safe Silicone Sealant is one of the best multi-purpose sealants. 

Also Read: Nano Reef: 10 Steps For A Quality Setup

Buying Guide

Apart from these 9 best aquarium silicone sealants, numerous other products exist in the market. Some of them are even better in terms of pricing and reputation. Therefore, we’ve gathered the parameters we tested these products for and have detailed them for you below. 

100% Non-Toxic Silicone

Typically, aquarium-safe silicone sealants are labeled accordingly. If a manufacturer doesn’t want you to use their product in your aquarium, please refrain from doing so and buy products that are labeled “solventless,” “100% non-toxic silicone”, or “zero fungicides”.

Many silicone sealants, that aren’t made for aquariums, contain fungicides to stop mold. 

Clear or Black

As an aquarist, you may have a preference for black or transparent silicone sealant. Black silicone is mostly used for ponds, turtle tanks, and aquariums with deep black substrates. However, quality and application-wise, it doesn’t matter what color you use in which aquarium. 

Type of Aquarium

Most silicone sealants made for aquariums are suitable for both freshwater and saltwater tanks but do verify it from the product label. In rare cases, salt water can damage the silicone seals in the long term and cause leaks.

Curing Time

Mostly two methods are used as curing systems for aquarium silicone sealants: acetoxy and neutral curing. Acetoxy curing releases acetic acid but is quicker. Neutral curing, on the other hand, releases alcohol and other less corrosive chemicals but is slower. However, acetoxy curing is more common in the aquarium industry.  

Resistance to UV and Retaining Flexibility

It’s critical for a silicone sealant to retain its flexibility. The temperature changes often put stress and strain on the bonds, which, if not flexible, can crack or shrink. Resistance to UV and other chemicals often ensures that a sealant will remain flexible in the coming years. 

Also Read: Best Wave Makers For Your Aquarium

FAQs

The Bottom Line

We’ve listed 9 best aquarium silicone sealants that have proven themselves to be worthy to go into your fish tank. These are safe and premium options that you can use to build or repair your aquariums. If vetting other products, please follow the buying guide compiled for you.