Irrespective of the building material used, waterproof silicone is integral to the aquarium building process. Aquarium silicone makes a covalent bond between two surfaces, acrylic or glass, and creates a long-lasting, waterproof joint. It also finds use in aquarium repairs and decorative fixtures.
While most aquarium silicone products are resistant to both salt and freshwater, some products may be limited by it. Therefore, it’s worthwhile to be sure about their scope of usage and limitations.
In this article, we’ll discuss the features that you need to look into when buying the best aquarium silicone brands and review a few products that we find worthy of your time.
Table of Contents
Flexibility and Weather Resistance
Aquariums are constantly filled with water, creating pressure. This pressure moves the surfaces slightly and causes stress on the joints. The flexibility of silicone in the joints ensures that it can expand with the glass and still hold the surfaces together without tearing or leaking—preventing breaches that may harm aquatic and human life.
Humid weather and UV radiation in aquariums may cause significant issues like molding and drying in silicone.
Weather-resistant, especially UV-resistant silicone products are especially preferable for aquariums to prevent crusting and leakage.
However, do avoid anti-mold silicone with fungicides and mildewcides, for they can flow into the water and contaminate the tank.
SELSIL Aquarium Silicone Clear Sealant
Available in 300-gram packs and suitable for caulking guns, the SELSIL Aquarium Silicone Clear Sealant is a popular choice for aquariums due to its advertised high elasticity, fish safety, and solvent-free formula. It creates strong bonds with both glass and acrylic to deliver a flexible yet strong bond.
- High Elasticity
This sealant boasts excellent elasticity. This allows it to accommodate movement and prevent leaks in dynamic aquarium environments.
- Fast Curing Time
The outer layer is cured in a few hours, while the whole thing takes 24-48 hours to cure.
- Safe for Fish
Formulated without harmful chemicals like solvents and acetic acid, this sealant is safe for both freshwater and saltwater fish.
- 100% Solvent-Free Silicone
Unlike traditional silicone sealants, SELSIL’s formula is free of harsh solvents, making it almost odorless and easier to clean up.
- Ozone and UV-Resistant
This sealant is resistant to ozone and UV degradation, ensuring long-lasting durability even in aquariums with ozone generators.
- Not recommended for porous materials like concrete or natural stones.
Curing Process and Time
Depending on the product, aquarium silicones usually employ two types of curing methods. Acetic acid cure (AA) and neutral cure. Acidic acid cure, being assisted by additional chemicals, generally cures faster, taking around 24 to 48 hours. However, they release a strong vinegar-like smell during curing and remain unsafe for fish until the odor completely dissipates.
Neutral cure, on the other hand, doesn’t contain acidic acid or release an odor as strong as AA cure. This type of curing process is typically slower and takes around 72 hours to fully cure. However, they are considered fish-safe as soon as the silicone sets.
Curing time often varies with the thickness of the application. A thin bead used for leak repair, for example, might cure within a few hours, whereas thick surface seals may take several days.
ASI Clear Aquarium Silicone Sealant
One of the best non-slump sealants, ASI Clear Aquarium Silicone Sealant, is a versatile and reliable choice for most aquarium sealant and adhesive needs. It comes in 10.2 Oz caulking gun-friendly containers and is formulated to work with both fresh and saltwater aquariums.
- Non-Slump Silicone Sealant
Non-slump property of ASI allows for a more even application on vertical surfaces. It doesn’t flow or sag during application and ensures proper sealing between surfaces.
- Wide Application Surface Temperature
The silicone solution can be applied to surface temperatures from 0F to 120F and is expected to withstand constant temperatures between -70F to 450F.
- 100% Aquarium Safe Silicone
No toxic solvents or anti-mold agents have been added to ensure the safety of the aquatic creatures. It also attained VOC compliance for not containing isocyanates.
- Usable on Multiple Surfaces
It can be used on multiple surfaces, including rocks, wood, and acrylic. You can anchor plants, build caves, and stack PVC pipes with the ASI silicone sealant.
- The odor is pretty intense
Adhesion to Various Surfaces
Aquarium silicone sealants excel at adhering to various surfaces and creating watertight seals suitable for aquatic environments. While silicone sealants find most of their usage on glass and acrylic surfaces, they are also used on natural rocks and stones to build complex structures.
When choosing an aquarium silicone brand, ensure it can satisfy your requirements and adhere to the surfaces you’ll be focusing on. For example, the porous nature of rocks and stones may demand special consideration and not allow generic silicone sealants to be used on them.
In contrast, if you’re considering using silicone sealants on metals, make sure to determine the compatible metals and prepare them by degreasing and roughening up the surface.
Apel Aquarium 100% Silicone Sealant
Made with different purposes in mind, Apel Aquarium 100% Silicone Sealant creates a strong bond that’ll remain flexible for years to come. It stops leaks, seals seams, and helps with your tank decorations. Packaged in 10.4 Oz containers, it completely cures in 24 hours with the outer layer drying in just a few hours.
- Acetoxy Curing System
Apel uses an acetoxy curing system, meaning it cures by reacting with moisture in the air. This makes it relatively fast-curing, typically taking 24-48 hours for a full cure. The process releases acetic acid fumes.
- Wide Temperature Range
The sealant is able to withstand temperatures ranging from -60°F to 300°F, making it suitable for most areas with extreme climates. However, ensure the water temperature is maintained throughout for the well-being of your fish.
- UV Resistance
Apel silicone sealant is UV resistant and doesn’t degrade in flexibility and durability with extended exposure to weather elements. It also prevents atmospheric ozone from reacting with the seal.
- 100% Silicone Sealant
This sealant is made from 100% silicone and doesn’t contain mold-resistant agents and mildewcides.
- Pretty strong odor.
Silicone sealants are negatively affected by a number of chemicals that either exist in the atmosphere or in the aquarium. For starters, high levels of ozone in the air can weaken the bond and reduce silicone degradation. Airborne contaminants may also reduce the flexibility of the silicone and cause a breach.
Apart from that, extremely acidic or alkaline water and cleaning agents may degrade silicone. Furthermore, as aquarium silicone products usually avoid fungicides, mold and mildew growth can destabilize the silicone bonds. Organic solvents, such as acetone, MEK, and toluene, may also weaken and dissolve silicone.
Aquarium silicone manufacturers often employ different methods to prevent or delay the occurrence of these chemical and biological reactions. However, it’s your responsibility to maintain your aquarium water regularly, inspect for signs of cracking, and avoid using cleaning agents on silicone.
Aqueon Aquarium Silicone Sealant Clear
Presented in 10-ounce standard caulking cartridge packs, the Aqueon Aquarium Silicone Sealant stands out as a top-tier transparent silicone sealant renowned for maintaining flexibility even after curing and extended use. It is also offered in a black variant, providing excellent value for those seeking high-quality options. Following the manufacturer’s instructions ensures a relatively longer shelf life.
Aqueon’s commitment to permanent flexibility ensures that bonds remain crack-free and unaffected by shrinkage during fluctuations in water temperature within the tank.
- 100% Non-Toxic Silicone
Crafted with 100% non-toxic silicone, this product is entirely safe for aquarium use. It is free from non-molding agents and oxime content, contributing to its aquarium-friendly nature.
- For Both Freshwater and Saltwater Aquariums
Designed for versatility, this sealant is suitable for both saltwater and freshwater aquariums. Its stable silicone composition prevents saltwater from corroding the bonding.
- Cures in 48 Hours
While 24 hours may be sufficient, our experience suggests that allowing 48 hours for the sealant to cure results in maximum strength. Patience during the curing process is key to optimal performance.
- Strong odor; it is advisable to work in a well-ventilated area.
Also Read: Aquascaping Styles For Aquariums
Aquarium silicone bonds are exposed to temperature changes to a great extent. From directly being subjected to sunlight throughout, they may also get exposed to sub-zero temperatures in some areas. Therefore, two types of temperature resistance are necessary for an aquarium silicone sealant to be practical.
Application temperature refers to the temperature range that is safe for effectively applying the silicone sealant. While manufacturers ideally recommend the range of application in the package, 50-90F is considered a safe application temperature.
A temperature that is too cold can hinder the curing process and weaken the bonds, while very high temperatures can dry out the silicone too quickly, resulting in uneven sealing.
Operating temperature, on the other hand, refers to the temperature range that the silicone bond can withstand after being completely cured. This typically ranges from -40F to 200F, with some manufacturers claiming a wider operation.
Choose aquarium silicone brands that can withstand hot summers without melting or degrading and tolerate sub-zero temperatures without cracking.
Aquascape Black Silicone Sealant
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Tailored specifically for pond liners and aquariums, the Aquascape Silicone Sealant is available in 10.1 oz caulking cartridges. Boasting both black and clear variations to cater to diverse application needs, including the repair and construction of fish tanks, it proves effective in both saltwater and freshwater environments.
- Unique VOC Compliant Formula
Utilizing a black dye formula that is VOC-approved, this silicone ensures the safety of your fish and other aquatic inhabitants.
- Can Withstand Extreme Temperatures
While we haven’t personally tested this claim, the product asserts its ability to endure extreme temperatures ranging from -40 to 200°F.
- Allows Water Contact in 30 Minutes
Under ideal conditions, the product permits water contact in approximately 30 minutes. However, it is advisable to exercise patience and wait at least 24 hours before introducing live fish or allowing prolonged water exposure.
- Exceptional UV Tolerance
Thanks to its VOC approval, Aquascape Black Silicone demonstrates exceptional UV tolerance. It remains resilient against long-term exposure, resisting bond breakage and crack formation.
- The silicone has a thicker consistency than usual and may require additional pressure for dispensing from the tip.
Silicone sealants are naturally mold-resistant to a degree. But to protect materials like wood and drywall from degrading quickly, manufacturers add fungicides and mildewcides to their products—claiming mold resistance.
We don’t want that kind of silicone in our aquariums. These toxic components leech into the water and often tip the balance of healthy aquatic environments. Only buy 100% aquarium-safe silicone, absent of any anti-mold agents or solvents.
While the exact information of anti-mold agents used in a product may be proprietary, a few inherent qualities of silicone naturally make mold difficult to survive. These include:
- The non-porous surface of silicone bonds provides no crevices for the mold to lodge and grow.
- Silicone is inert in nature and minimizes the availability of nutrients for mold to grow.
- The water-repellent properties of silicone don’t allow moisture buildup on the surface—discouraging mold growth.
Look for aquarium-safe labels to ensure your silicone sealant is non-toxic.
Also Read: Nano Reef: 10 Steps For A Quality Setup
Akfix 100AQ Aquarium Safe Silicone Sealant
Designed for aquarium applications, the Akfix 100AQ comes in a more compact 9.5 oz caulking gun cartridge package of transparent silicone. Its acetoxy curing system eliminates the need for additional heat or UV radiation to expedite the curing process, forming robust bonds on non-porous surfaces like glass, PVC, and acrylic.
- 100% Safe Silicone
Akfix is formulated of 100% solventless silicone without any fungicides, ensuring harmlessness to fish and other aquatic creatures.
- Acetoxy Curing System
The acetoxy curing system expedites the curing process, emitting a temporary acetic acid smell during drying. This system enhances the speed and uniformity of the curing process.
- Wide Application and Operational Temperature
Akfix 100AQ boasts an impressive operational temperature resistance ranging from -58 to 392°F and an application temperature range of 40 to 104°F. This broad temperature range makes it suitable for various applications.
- Remains Elastic for a Long Time
Thanks to its UV and chemical resistances, 100AQ maintains elasticity over an extended period, enduring stress and strain induced by temperature changes.
- The acetic acid smell may cause eye irritation and discomfort. It is recommended to carry out projects outdoors or in well-ventilated areas.
Transparency and Color Options
Aquarium silicone sealants typically come in two color variations: clear and black. The clear variation is mostly used in creating the joints and fixing seals. The black variation usually finds its application in the surface joints and the decorations of black-themed tanks. Apart from these two, more color options may also be available in your area.
Adhesive Guru Aquarium Silicone Sealant Clear
Formulated for aquarium construction and repair, the AG Aquarium Silicone undergoes curing through acetic acid release and is conveniently available in 10.5 oz caulking gun refills. Setting it apart from other acetoxy-curing silicone sealants, AG offers a more cost-effective solution and is packaged in a dry-proof sealed tube.
- No Additives or Fungicides
Tailored for aquarium use and crafted with 100% harmless silicone, AG Aquarium Silicone Sealant is free from solvents or fungicides, ensuring its safety for aquatic environments.
- Remains Flexible for Years
In line with premium alternatives, this sealant maintains flexibility over an extended period, mitigating the impact of stress and strain on the silicone bond.
- Safe to Touch After 2 Hours
Thanks to acetone curing, the silicone seal becomes safe to touch or expose to water after just 2 hours. However, for the introduction of fish and treated water, it is advisable to allow a full 24 hours for complete curing.
- For Both Freshwater and Saltwater Aquariums
This versatile product is suitable for both saltwater and freshwater aquariums, boasting a strong bonding capability that can withstand the demands of reef aquariums.
- The odor is quite potent. It is recommended to leave it in well-ventilated areas during the curing process.
While aquarium-safe silicone is 100% silicone, the opposite may not be true. As the manufacturers want to sell as many products as possible, they have zero incentive to leave out a potential customer base. Hence, only consider aquarium-safe 100% silicone for your tank.
Aquarium silicone is quite flexible and strong. The bonds formed between the surfaces can withstand extreme temperature changes and tolerate the stress and strain introduced by changing water pressure.
Aquarium silicone lasts for decades without degrading in flexibility and strength. However, extreme weather elements and some chemical solvents may reduce the lifespan of the joints.
The Bottom Line
We’ve discussed the best and safest aquarium silicone brands that you can choose from. Hopefully, you’ll now be able to fix aquarium seals, DIY aquariums, and craft complex decorations for your aquatic friends.