Homemade Aquarium Rocks

Rocks are a great addition to any home aquarium. Some fish, like the Mbuna cichlids, are rock-dwelling creatures and need a rocky aquarium to thrive. Though many shops sell prefabricated rocks, they do not always look like live, ocean rock formations. Achieve the desired look by making homemade aquarium rocks.

  1. Process

    • Begin by purchasing Portland cement and play sand from your local home improvement store. Portland cement comes in powder form and forms a paste when mixed with water. Type three cement works best for this project.

      To form a paste that easily forms into moldable balls, mix together one part cement and four parts sand. Use durable rubber gloves and wear a long-sleeved shirt when working with cement.

      Place damp sand into a bucket and carve out the shapes and sizes you wish to create. This will serve as a mold for your cement. Pour the cement mixture into the sand molds and shape it into the desired look. Use the process to create all sorts of shapes from standard rocks to caves. Get creative and tailor the look of this aquarium to suit your design. Allow the molded shapes to sit for at least 24 hours.

    Curing

    • Cement is highly alkaline and usually has a pH level between 12 and 13. Aquarium pH levels need to be between 8.2 and 8.4. Homemade cement rocks need to cure before they can be placed into a fish tank. Place the rocks into a bucket of water and add vinegar to speed up the curing process. Rocks will cure for at least three days, though the process can take as long as three weeks. Frequently change the water in the bucket and test the pH levels.

      Place rocks in aquarium once the pH levels of the bucket and tank match. Once the rocks are added to the aquarium, fish will begin to explore. They may use the newly formed rocks for shelter. Do not be alarmed if fish hide in the rock formations.

    Warning

    • Cement causes alkali burns when it contacts skin. Always wear durable rubber gloves and a long-sleeve shirt when working with cement. Alkali burns slowly deteriorate skin and may do so for several hours before the sufferer notices. Thoroughly wash the affected area with clean, running water for at least 20 minutes. Adding vinegar or lemon juice to the water helps neutralize alkaline. Do not use these products if skin appears to be blistered. Always seek medical attention for an alkali burn because the product can continue to damage skin even after washing.