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From aquarium substrate and decorative rocks, all the way to filter systems, water heaters, and air pumps, setting up an aquarium requires several essential elements to work together. One of the most important parts of an aquarium, and I think you would agree, is the silicone sealant.

Aquarium safe silicone is a real lifesaver when it comes to fixing minor or major leak issues. Silicone sealant provides a quick solution to save your aquarium inhabitants, whether fish or plants, from injuries and stress. It’s also pretty handy to use as an adhesive if you want to attach something to the glass of the aquarium.

The best thing about aquarium safe silicone, besides being non-toxic to your aquarium inhabitants, is that it lasts for years upon years once cured.

Today, we’re taking a closer look at aquarium safe silicone to provide you with all the information you need before making a purchase. We’re also including a list of the 6 best aquarium safe silicones to help you land an awesome deal. Let’s dive in!

Our Top 6 Aquarium Silicone Products You Can Feel Safe Using In Your Aquarium

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What is Aquarium Safe Silicone and How does it Work?

First things first, you should understand what aquarium silicone actually is and how exactly it works.

As you can probably tell, aquarium silicone is a type of sealant that’s primarily made of silicone. Consequently, it’s known to offer a tough and reliable performance when it comes to adhesion jobs. This is why silicone sealants can be used in a wide range of applications, not just for aquarium maintenance purposes.

Silicone sealants can endure extreme temperatures and resist ultraviolet rays. They also come with excellent movement attributes and high versatility, making them the top choice for aquariums.

But it doesn’t stop there! What makes silicone sealants particularly useful in aquarium situations is that silicone is one of the very few adhesive materials that actually clings to glass – which makes up most of any aquarium.

So how does aquarium silicone work? This sealant holds together your fish tank by securely binding glass parts. This includes fastening any damaged areas or leaky spots in your aquarium.

You should know, however, that silicone doesn’t bond immediately after application like super glue. Instead, it goes through a process called curing where it usually takes about one week for silicone to completely cure as it slowly dries.

You can recognize if your silicone sealant is still curing by being wet to the touch and smelling like salt and vinegar chips.

It’s important to note that silicone doesn’t cure underwater, so if you apply it with water inside the tank, it won’t dry out. Silicone sealants should be air-dried until they’re completely cured to be deemed aquarium safe.

Here is a great video by Joey about Aquarium Safe Silicone

What is the Difference between Regular and Aquarium Safe Silicone?

Now, you’re probably wondering about the difference between regular silicone and aquarium safe silicone. Why can’t you just use them interchangeably?

While both products offer similar performance in creating strong bonds for sealing and repairing leaks, cracks, or other damages, regular silicone is meant to tackle an array of applications in building and household projects.

As for aquarium safe silicone, it’s designed in a specific manner to be non-toxic to fish and aquatic plants, keeping them safe and healthy even after curing.

Generally speaking, you want to look for a sealant that contains 100% silicone. Read the label carefully because some manufacturers will claim 100% silicone content but they actually use other additives that are usually stated in the fine print. Don’t worry too much though, reputable brands like the ones we’re listing today are true to their label claims.

That being said, if you notice the terms Mold-Free, Mildew-Resistant, Anti-Microbial, or Bacteria Protection on your tube of silicone, do not use it in your aquarium. Such products contain fungicides and bactericides that may end up killing your fish and aquatic plants.

Why Use Aquarium Safe Silicone?

Aquarium safe silicone is an excellent solution to fix minor leak issues or attach objects to the glass of your fish tank. But what makes it better than other sealant types on the market?

Well, here are some benefits that accompany using aquarium silicone:

  • It’s non-toxic to fish and aquatic plants.
  • It contains authentic silicone so they’re safe to apply in any glass aquarium.
  • It’s transparent so it won’t interfere with the overall appearance of your aquarium.
  • Once cured, the silicone seal isn’t at all affected by the constant submersion in water.
  • It works great for both freshwater and saltwater tanks.
  • It resists cracking, shrinking, sagging, or drooping.
  • It’s easy to apply and forms very strong bonds.
  • It resists ultraviolet radiation, ozone, and airborne chemicals.

Then, are aquarium safe silicones simply perfect? They’re extremely handy, no doubt about it, but there are a couple of drawbacks involved with such seals.

For one, silicone sealants don’t cure when wet. They take around 7 days to completely cure, and they’re not quite suitable for acyclic tanks.

How to Use Aquarium Safe Silicone?

Although there might be slight variations among the different brands of aquarium safe silicone, the application process is generally the same. Here’s a step by step guide for using aquarium silicone:

  • Drain your fish tank and make sure it’s totally empty.
  • If there’s any old silicone where you want to apply the new seal, use a razor blade to get rid of all old silicone. (More on the removal process later)
  • Prepare the area to be sealed by cleaning it up and smoothing it out with sandpaper. This roughens the surface a bit to ensure a stronger hold.
  • Make sure all the surfaces are completely dry. As we mentioned above, the silicone sealant doesn’t dry when wet.
  • Gently apply silicone beads at the site of the leak or along the tank’s edges. Here, you can use a caulking gun or the applicator that comes with the tube.
  • Use fortified duct tape to make sure all corners are tightened. If you own an aquarium sized more than 75 gallons, then wooden clamps are a better option to hold everything in place while the sealant cures.
  • Using your finger, smooth the silicone along the seams to remove excess product and create a sleek surface.
  • After that, you just need to wait until the curing process is finished. In general, it takes about 1 to 2 days for aquarium silicone to dry, but it can take up to a whole week for it to completely cure.

How to Remove Aquarium Safe Silicone?

When it comes to removing aquarium silicone sealant, there are a couple of methods you can use depending on how much silicone you want to get rid of.

If you’re dealing with a smaller seam or area, you can simply use a razor blade to scrape off the silicone. This is a pretty easy and quick way to get any sealant off the surface, but it doesn’t work all that well if you need to remove a lot of silicone. Not only will it leave many tiny bits of sealant behind, but it’ll also cost you much time and effort.

If you want to remove aquarium silicone from a large area or from the corner seam, you should start off by using a heat gun or a hairdryer to blow hot air onto the silicone seal. Note that a hairdryer will take a lot more time to provide the same effect as a heat gun because it doesn’t get as hot, however, it’ll eventually get the job done.

Once the silicone is warmed up enough to become more flexible, use a razor blade to scrape it off. Remember, you don’t want to melt the silicone, just get it softer so it’s easier to remove. After you’re done, go in with a textured sponge and scrub away anything left behind.

6 Best Aquarium Safe Silicones

1. ASI Clear Aquarium Silicone Sealant

Clear Aquarium Silicone Sealant - 10.2 Fluid oz Cartridge

Get ASI Clear Aquarium Silicone Sealant

Specifically designed for aquariums, this Clear Aquarium Silicone Sealant from ASI offers excellent tensile strength and tear resistance. It doesn’t require the use of primers to form solid cohesive bonds with glass, which means you don’t have to worry about prepping.

Once it completely cures, the produced tight seal remains unaffected by continuous immersion in both freshwater or saltwater tanks. It’s so good that it withstands constant stress on aquariums up to 750 gallons, operating from -70°F to 450°F (-57°C to 233°C).

Pros

  • Remains intact under immense stress
  • Withstands extreme temperatures
  • Doesn’t need primers

Cons

  • Dries too fast for some users

2. Aqueon Silicone Sealant

Aqueon Silicone Aquarium Sealant (10.3 oz)

Get Aqueon Silicone Sealant

Highly effective and reliable, the Aqueon Silicone Sealant is one of the top-rated aquarium sealants with hundreds of positive reviews to back it up.

Made out of 100% non-toxic silicone, the Aqueon Silicone Sealant is safe for all fish and any aquarium. It creates a strong, waterproof seal that won’t shrink or crack. It’s also permanently flexible with a super-easy application that dries out very fast for quick solving of leaks.

My Favorite Filter
AquaClear HOB Filter

The AquaClear HOB filter has been around FOREVER and is typically the first filter recommended for most beginners. That said, it's a great reliable filter for experienced fish keepers and Aquascapers. It comes with prepackaged filter media but also has the ability to customize to your needs. Don't worry about water flow as the gentle waterfall design creates oxygenation without a strong current perfect for small tanks and Bettas.



This long-lasting aquarium safe silicone won’t leave behind any traces or stains, so your tank will look as good as new without any damaged appearance.

Pros

  • Very easy to apply
  • Permanently flexible
  • Dries fast

Cons

  • On the pricey side

3. Loctite Clear Silicone Waterproof Sealant

Loctite Clear Silicone Waterproof Sealant 2.7-Ounce Tube (908570)

Get Loctite Clear Silicone Waterproof Sealant

When it comes to accurate sealing, the Loctite Clear Silicone Waterproof Sealant is one of the absolute best products for the job. Not only is it formulated to never peel, crack, or shrink, but it’s also suitable for use with either freshwater or saltwater aquariums.

The Loctite Silicone Sealer is quite versatile, bonding a wide array of materials including glass, ABS, wood, porcelain, ceramic, fiberglass, and stainless steel. It’s made out of clear, authentic silicone, so it’s guaranteed to not harm your aquarium inhabitants.

Pros

  • Binds a wide variety of materials
  • Handy size
  • Affordable

Cons

  • Packaging bursts easily

4. ASI Black Silicone Sealant

Black Aquarium Silicone Sealant - 10.2 Fluid oz Cartridge

Get Black Aquarium Silicone

Not everyone wants a clear sealant to fix a leak or patch a pond liner, sometimes black is best. If you’re on the same page, then you’re going to love the Aquascape Black Silicone Sealant.

This non-toxic silicone sealant creates a durable, watertight bond that’s not compromised by continuous exposure to water. Thanks to its black color, this sealant will give you an invisible repair that works beautifully with ponds, aquariums, and terrariums.

You should expect, however, a particularly strong smell upon applying this sealant, so be sure you do it in a well-vented space.

Pros

  • Creates an unnoticeable black seal
  • Works great for aquariums and ponds
  • Very durable

Cons

  • Smells a bit too strong

5. Dap 00688 All-Purpose Adhesive Sealant

Dap 00688 All-Purpose Adhesive Sealant, 100% Silicone, 2.8-Ounce Tube

Get Dap All-Purpose Adhesive Sealant

This reliable all-purpose sealant is certified as aquarium safe. It’s odorless, dries clear, and stays flexible after application.

The Dap 00688 All-Purpose Adhesive Sealant is very easy to use, allowing you to simply scrape it off or cut it even if you accidentally squeezed out too much or put it over the wrong area. This makes it a good choice for the not-so-handy aquarists.

This 100% silicone sealant is safe for all fish in freshwater or saltwater aquariums. It won’t crack or shrink, also suitable for use with metal, ceramic, and concrete.

Pros

  • Remains flexible
  • Versatile use
  • Good for the less handy aquarists

Cons

  • Small size

6. Marineland Silicone Squeeze Tube

MarineLand Fish & Aquatic Supplies Silicone Sealer 1 oz (Tube)

Get Marineland Silicone Squeeze Tube

Last but not least, the MarineLand Silicone Squeeze Tube is a clear 100% silicone sealant that’s specifically formulated for aquarium use. It delivers a solid bond with an impressive grip that dries pretty quickly to save you the hassle of waiting.

The MarineLand silicone sealant stays flexible even underwater. It comes in a sturdy tube so it won’t easily burst out like other brands. However, the long, narrow nozzle can make the application a bit tricky.

Pros

  • Study packaging
  • No irritating odor
  • Good value for money

Cons

  • The nozzle is a bit too narrow

Wrap Up

It’s rather evident that aquarium safe silicone sealants are a must-have item for any serious aquarist, and so, you should be very careful when shopping for the right sealant.

Make sure your silicone sealant comes from a reputable brand to guarantee the utmost credibility. Also, remember to thoroughly check the label for any harmful components as we mentioned above.

Aquarium Safe Silicone