DIY Plastic Foam Aquarium Background

Custom 3-D aquarium backgrounds are becoming more popular at pet and specialty stores across the country. While these backgrounds are indeed stunning additions to an aquarium, the hefty price tag can be inhibiting for many fish owners. Another option is to create your own aquarium background from Styrofoam; not only will this save money, but you can customize your background to any size and shape you want, making your tank truly one-of-a-kind.

Things You'll Need

  • 2-inch thick plastic foam sheeting
  • Serrated knife
  • Heat gun
  • Concrete mix
  • Concrete pigment (optional)
  • Aquarium silicone
  • Water bottle
Show More

Instructions

    • 1

      Measure the back wall of your aquarium, and cut two pieces of plastic foam to fit this dimension. Attach the two sheets together with foam spray insulation, and press them together with a few heavy objects to dry overnight.

    • 2

      Begin carving into the face of the plastic foam with a serrated knife, creating outlines of rocks, caves, and shelves. Use your imagination, and try not to make the background symmetrical. Varying the shapes and sizes of the rocks is another way to add realism, and looking up images of other projects (or even natural rockscapes in nature) will help you develop your idea.

    • 3

      Use the heat gun to smooth over the rocks and add depth to your texture. You can also opt to use sandpaper and a blow dryer for this step if you do not have a heat gun available. Work in layers, and don't be afraid to pick up the knife and make more adjustments.

    • 4

      Cut the background into two or three sections to make sure it will fit in the aquarium. Make your cuts along lines in the rocks to disguise the seam. Check the fit of the background, and make final size adjustments now before moving on.

    • 5

      Mix the concrete to a soupy, paint-like consistency, and apply to the exposed faces of the plastic-foam background in layers. Each layer will take two to four hours to dry and should be kept moist by misting occasionally with a water bottle to prevent cracking. Continue applying layers and building depth, optionally adding concrete color pigment to the last few layers for a punch of color.

    • 6

      Silicone the background into place using aquarium-safe silicone, and allow to dry for 24 to 48 hours.