How to Make Your Own Aquarium Rocks

If you are designing your own aquarium, you may have found it difficult to find just the right rock structures to get the look you want. Also, you have likely found that buying aquarium rocks is hard on the wallet. Save some money and get the exact rock structures you want and need by making your own aquarium rocks. All you need is some cement and a few items you probably have in your house or garage.

Things You'll Need

  • Large plastic tub
  • Sand
  • Portland cement
  • Wooden stir stick
  • Fine gravel
  • Rubber gloves
  • 5 gallon bucket
  • White vinegar
  • pH meter
Show More

Instructions

    • 1

      Fill the plastic tub with damp sand. You will use this sand to create molds for your rocks, so dig out some holes in the sizes and shapes you want.

    • 2

      Mix up your cement. Generally, this will simply involve adding water to the mix, but because every manufacturer is slightly different, you will need to check the package for exact measurements.

    • 3

      Add the fine gravel to the cement. This will enable you to mold the cement. If you are going to pour the cement into the molds in the tub only, then you can stop adding gravel when the consistency of the cement is still pretty runny. If you want to mold by hand, you will need to keep adding gravel until the cement is almost like play dough.

    • 4

      Make your rocks. You can pour the cement and gravel mixture into the sand molds you made earlier or you can mold by hand. Be sure to wear your rubber gloves if you are going to handle the cement. You can lay molded rocks on top of the sand to set.

    • 5

      Let the rocks set. This may take 48 to 72 hours if the weather is humid. Keep them in a warm, dry place until they have set completely.

    • 6

      Cure the rocks for three days for a freshwater tank or three weeks for a saltwater tank. Place the rocks in a bucket of water that contains a cup of white vinegar. Change the solution often. The rocks are safe to put in with your fish when the pH of the water in the bucket is the same or nearly the same as that of the water in your aquarium.