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3 Common Drilled Tank Aquarium Questions Answered!

When it comes to aquarium keeping, we’ve come a long way from having a single goldfish in a bowl. Modern aquariums can be hundreds of gallons and contain fish from all over the world, and the most impressive of these tanks are no doubt saltwater reef tanks.

Saltwater reef tanks are filled with plants, colorful fish, and stunning reef fixtures, but these gorgeous tanks come with some upkeep. 

Like with most hobbies, there is terminology in aquarium keeping that you won’t hear elsewhere, and one of these terms you will hear in saltwater aquarium keeping is drilled tank.

Drilled tanks, which are sometimes called reef-ready tanks, are different from the basic glass or acrylic aquariums you can buy off of any pet store shelf, but what exactly makes them so special? 

Picking out a new saltwater tank can seem overwhelming, but with a little bit of information, you can be educated when making your new tank purchase!

In this article, we’ll answer the 3 biggest questions in regards to drilled tanks by explaining what a drilled tank is, how to seal a drilled tank, and if drilled tanks are appropriate for beginners.

What Is A Drilled Tank?

A drilled tank is a fish tank that has holes pre-drilled in it so you can insert different hardware into the tank, usually an overflow pipe for filtration. Tanks can come pre-drilled, be drilled by professionals after purchase, or be drilled at home.

Due to the intricate filtration methods used in saltwater aquarium keeping, there can be a lot of components that come with a tank that drilled holes can help hide. 

Saltwater tanks have a number of different systems needed to run correctly, and keeping the fish, plants, and coral healthy in these tanks is an intricate process.

When a tank isn’t drilled, the hardware for these systems must be placed on top or below the tank, which can appear bulky and unsightly.

With holes drilled in the back of the tank, the overflow hose for the tank’s filtration can be hidden from the site, allowing the tank to have a more streamlined look. 

Reef tanks are made from either glass or acrylic, and surprisingly, both types of tanks can be drilled.

New aquarium owners may think that a glass aquarium with holes might not be structurally sound, when in fact they are, especially if the tanks have been professionally drilled.

Drilled aquariums almost always have the holes drilled in the side of the tank, because the bottoms of the tanks are made from tempered glass, and while tempered glass can bear the weight of the water and substrate easily, it will shatter when drilled. 

How Do You Seal A Drilled Tank?

If you’ve bought a second-hand drilled aquarium and you aren’t planning on using the holes for anything, you’re going to have to seal them.

Drilled holes that aren’t sealed correctly can have catastrophic consequences if the seal fails, leading to flooded aquarium rooms and tons of damage. Sealing the holes is simple and requires nothing but aquarium safe silicone, and either glass or acrylic.

There are two ways to seal drilled holes in a tank. The first is to fill the holes with aquarium-safe silicone until they are watertight or to use a piece of glass or acrylic to cover the holes and then adhere them to the aquarium with aquarium safe silicone.

Sealed aquariums often work just as well as ones that were never drilled, but it’s a good practice to always keep a close eye on the sealed portions of the tank for any leakage. 

Which method is best for your tank will depend on how large the drilled holes are. Small holes can be easily filled with silicone, but larger holes should always be covered by glass or another sort of cover or plug first before being sealed with the silicone.

Not all silicone is created equal, though, and it’s imperative that you make sure your silicone is aquarium safe so it doesn’t leech toxic chemicals into your tank water. 

Are Drilled Tanks Beginner Friendly?

Drilled tanks are beginner friendly if they are bought pre-drilled, but drilling an aquarium yourself should be reserved for professionals.

If you already own an aquarium that is not drilled and you want to have it drilled, it’s best to seek out someone with experience so you don’t accidentally compromise the structural integrity of your tank.

Glass is especially difficult to drill, so if you’re looking into a glass drilled aquarium try to buy one that is pre-drilled and ready to set up.

The best drilled aquariums for beginners are called reef-ready aquariums, and these tanks come with pre-drilled holes as well as all the other hardware necessary to set up a saltwater reef tank, taking the guesswork out of starting a tank.

Acrylic tanks are more forgiving for beginners and are much less likely to shatter when drilled, but you should still use caution if you’ve never drilled holes in a tank before. 

Using a drilled tank can seem intimidating to newcomers to the hobby, but tank owners often find drilled tanks to be easier to set up since you don’t have to worry about hanging everything off of the lip of the aquarium or finding space to place the hardware underneath.

One thing to note is that drilled ranks are almost always used for saltwater tanks and not freshwater tanks, because the filtration in a saltwater tank is more complicated. 


A drilled tank is just a fish tank with holes drilled into it for for hoses and filtration. These tanks are usually used for saltwater setups and can improve the ease of tank setup and the appearance of the aquarium overall. Not all saltwater tanks have to be drilled, and you can even reseal previously drilled holes in your tank if you want to. You can also have holes drilled into a tank that you already own to make it into a drilled tank. These types of aquariums can seem complicated, but with a little research they are relatively beginner-friendly.