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3D Aquarium Backgrounds – A DIY Guide


Posted January 21, 2012 by

3D Aquarium Backgrounds – A DIY Guide

You’re probably here because you’ve seen a beautiful 3D aquarium background on the internet somewhere.  You probably want a 3D aquarium background for your own tank, but think it is hard to do.  While it isn’t the easiest project in the world, it isn’t too difficult to make a realistic aquarium background for your tank.  The basics of this tutorial are rather easy, but it’s the finesse of the crafter that can really make one of these DIY aquarium backgrounds pop.

If something like the above image is what you’re after, you’re in luck.  Because this article covers how to make this aquarium background, step-by-step.  Note:  The tank pictured above is owned by ReepiCheep.

Let’s get started with the materials list.  Here is everything you’ll need to create a 3D aquarium background for your own tank:

  • Silicone Tubes (GE Silicone I is safe for aquariums)
  • Styrofoam Sheets
  • Miscellaneous Styrofoam Pieces
  • GS Foam Can
  • Sandpaper
  • Carving Knives
  • Drylok
  • Concrete Dyes (Black and Brown)
  • Thick Bristle Paintbrushes

Now that we have the materials we need, let’s start assembling our 3D aquarium background.  The first thing we are going to want to do is to create a very basic framework with our styrofoam sheets.  The background in this tutorial uses three layers of styrofoam, cut to create depth for the background.  Once you are happy with the mock-up, silicone the pieces tightly together.  It is important to apply even pressure to the pieces when bonding them together.  The pieces should fit together well with no obvious voids.

Once the styrofoam sheets are siliconed together nice and tight, begin siliconing in miscellaneous pieces of styrofoam to create features within the background.  Styrofoam pieces from packaging boxes and styrofoam balls from a craft store work well.  Typically, it is best to taper the 3D aquarium background so that the basic shape is thicker at the bottom and thinner at the top.

After the basic shape and structure of the background is established (give the background a day or two to dry after applying silicone to it), begin carving!  Carving the 3D aquarium background is probably the most difficult step in getting it to look realistic.  Don’t be daunted by this task, though.  If you make a mistake, just tack on another piece of styrofoam or use expanding foam from a can to fill in any gaps or errors.  The most important thing is to take your time and have a plan in your mind of what you want it to look like before you start carving.

Note:  Make sure that your 3D aquarium background fits snugly into your aquarium at this point.  If you will need to cut it into sections in order to fit it in, now is the time to do it (before painting and sealing it in concrete). 

After carving the background out and defining the finished shape of your background, it is time to start painting your background with the Drylok and concrete dyes.  Mix the Drylok with the dyes in separate containers in different ratios of brown and black.  Create a palette of color shades from black to medium brown.  Paint the Drylok on, one coat at a time.  The best method for covering the 3D aquarium background with Drylok is to tap the paintbrush repeatedly onto the styrofoam.  The bristles on the paintbrush will leave small indents in the styrofoam, creating a realistic stone texture.  Use the darker Drylok for the crevices, and the lighter shades for the protruding parts of the background.  Doing so creates the illusion of shadows and light within the background, adding depth to the 3D aquarium background.

Note:  Be careful not to add too much black Drylok to the background.  Solid black doesn’t look very natural.  A dark gray is better suited for most of the coverage in the crevices of the background.  Your aquarium lighting will take care of the rest.   

Tip:  If you want more of a woody look for your 3D aquarium background instead of a stone appearance, use more shades of brown in your background, and drag the bristles of the paintbrush along the styrofoam.  This will create a woodgrain look. 

Now that the background is covered in 3 coats of Drylok, it should be good to go after drying.  Look over it a couple times to make sure every bit of the styrofoam is covered (except for the back panel).  If the background is thoroughly covered, begin putting it into your aquarium.  Use silicone to tack the background to the back of the tank and into place permanently.  Be sure to cover all of the seams with a solid bead of silicone.  If there are any gaps, water will get behind the background, which is something we do not want to happen.

Let the completed 3D aquarium background dry for a couple more days before adding water to the aquarium.  The Drylok will mess up the water chemistry for awhile, so adding some salt to the water and doing water changes a lot will help to get rid of the leached substances from the Drylok.  Test the water regularly and be absolutely sure that all parameters are correct before adding any inhabitants to the tank.

Here is a beautiful example of what can be done from just a few sheets of styrofoam and some Drylok:

The pictures used in this article are the property of ReepiCheep.  Please do not use or replicate the above images without the consent of ReepiCheep.


Corey is the primary author and editor on Critterhub. With over 20 years of pet care experience, his interests lie mostly in aquaria and herpetology. Corey has a degree in Biology, and has completed many research projects involving herpetology and other animals.



    How hard is the painting part of it? Should you start out with a light colored base and just make it increasingly darker from there? Or? Thanks!


    Painting it is rather easy. And yes, I would just start with a basecoat and go from there with the shading.

    Like the article says, try to stay away from using black. Use medium to dark tones and let your lighting do the rest to really make the shadowing pop.


    Hi im just about to make the 3d background but what I wanted to know is, how do you know what dye or paint to use that wont kill the fish? Would hate to give this to my gf who loves her fish bowl and it kills all her fish haha? Amazing idea and well described otherwise, Thanks in advance.


    Hi corey, I’d like to discuss a business idea with you. I like your work on the aquarium background. Please PM me. Thanks.

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