| Home-made
Rocks for the Mbuna Aquarium
by Jeffrey Legitt
Of Tacoma, Washington
Aquarticles
I recently set up a new 125 gallon Malawi Mbuna tank for my family room. I wanted the
aquascape to include a lot of rocks, but I also wanted it to look natural. I tried slate,
river rock and even commercially sold holey rock. None of these looked natural, so I
started researching on the internet for other types of rocks and came across Geothermal
Aquaculture Research Foundation [garf.org]. They had several articles detailing how to
make live rock out of cement and aragonite called Aragacrete™. Aragacrete™ has
been used for quite some time by reef keepers with great success. Following their example,
I decided to try my hand at a little rock making.
My first attempts looked like very good live rock, but didn't look natural for an
African cichlid tank, so I changed the recipe. I omitted the aragonite and used standard
play sand. Since this is what I use as a substrate, I was hoping it would blend in. It
worked perfectly. I made several pieces of sand rock with lots of holes and caves. Because
I formed the caves in a bed of wet sand, the sand adhered to the rock and blended
perfectly with the substrate. The number of holes and caves also made the rock very light,
making it possible to stack the rocks very high. I built enough rocks to stack them all
the way to the surface along the entire back and sides of the tank. My tank houses 23
Mbuna, including some of the more aggressive fish, with very little fighting. It is simply
too easy for the dominated fish to flee and hide. I'm very happy with my tank and
home-made rocks and I hope others will have luck with this technique also.
My recipe for home-made rocks:
One part Portland cement. (Type 3 is best, but 1 & 2 will work).
Four parts play sand. (Washing the sand will make stronger rocks).
- Mix cement and sand together to a pasty consistency. It should form balls in your
hand. Cement is very alkaline, so use rubber gloves when handling.
- Place a fair amount of damp sand into an appropriately sized container.
- Dig holes in the damp sand to form a mold. You choose the shape.
- Drop the cement mixture into the mold and form it with your hands.
- Additional damp sand can be used as a filler to create cave, tunnels and holes.
- Let sit for 24 hours before touching.
- Cure the rock! Cement is very alkaline and will raise your water's pH.
African cichlids thrive in high pH. I added a massive amount of home-made rock to my
tank after curing for only two days and my pH never climbed higher than 8.4. I list the
following curing methods simply because most people have had different results:
- Cure rocks in a bucket of water for several days - possibly several weeks - changing
water often. - - - - Soaking the rock in hot vinegar can speed the curing
process. Once the water in your curing bucket has a pH suitable for your tank, the rock is
cured.
That's it. I hope this helps somebody with their Mbuna tank aquascaping.
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