Aquascaping Rock Walls for a Reef Tank

As you may have seen from other posts I am setting up a new 225 gallon grow out tank for SPS. I have quickly run out of room in my other 225 tank and need more space.  I however do not want to just have a few egg crate racks and corals since I like to sit in front of the tanks too much.  To save on space I have decided to aquascape a rock wall for the back of this aquarium.  This way I can utilize the whole back panel of the tank for grow space and not just a rock pile or rock columns.  In this article I will cover the steps I took for aquascaping rock walls for a reef tank.

Aquascaping rock walls for a reef tank required several supplies which I have listed below.

I used egg crate to act as a base for my rock wall.


Black zip ties to hold the rock onto the egg crate.


Pond foam to fill in all the gaps between the live rock.


Busted up live rock.  If your busting up the live rock yourself, save the tiny pieces and dust to use later to sprinkle on your wet foam, It helps make the rock wall look a little more natural.


Lastly a dremel to shave down the foam where it expands off the egg crate base.


To start I cut up large sheets of egg create into smaller manageable pieces to be fit together inside the tank after the rock wall foam has dried.

I then took my busted up pieces of live rock and started to zip tie them onto my egg crate.  Place your larger pieces at the bottom of the egg crate so that your rock wall isn’t constantly fighting to topple over.  Also keep in mind that with your lights above your tank the way you organize your rock could cause shading on the rocks below, so if possible build your wall up to be skinnier at the top with smaller rocks. In some places I did places ledges on the rock wall on purpose knowing it would shade the lower rocks but I like the idea of placing high light requirement show piece corals on these ledges and also giving the rock wall more depth.  While aquascaping rock walls for a reef tank try to keep your rocks all the way on the egg crate and don’t let them hang over the sides. This causes a lot more work than is necessary for putting them all together later, which I learned the hard way.  In fact in the images below the rocks are hanging too far off the sides.



Once the rocks are all zip tied firmly to the egg crate it is time to fill in the gaps with the pond foam.  First off if your egg crate feels flimsy or will not stand up on its own don’t be worried this is to be expected.  Another thing to keep in mind is that the pond foam will expand a lot through the drying phase. Don’t fill in the gaps with a ton of foam or it will grow out past your rocks and will close over your live rock.  I prefer to foam my rock walls on top of cardboard.  As the foam seeps through the back of the egg crate it will dry and attach itself to whatever is underneath it and will make a huge mess.  When you rip the rock wall off the cardboard you might have to pick at the paper a little bit but its better than making a mess!  I also like to use cardboard since it will tear before you start bending and cracking your rock wall trying to remove it from whatever surface it attached itself too.  After you have applied all your foam sprinkle some tiny pieces of live rock onto the foam to just make it look a little more natural and like one piece.


I usually give my rock wall piece about a day to dry.  Once you rip it off your cardboard you will notice that the foam has expanded through the egg crate and caused the sides and bottom to be uneven.


This needs to be shaved down or it will not fit together properly in your tank.   I used a dremel to level out the foam so that it was flat on the sides and back.  On the back of the rock wall I did not shave it to be totally flat with the egg crate.  I let the foam stick out a little bit on the back, but still flat.


Something I discovered when I put the rock wall in water is that even with so much live rock weight the foam still made the wall float!  To make the rock wall stay in place and not float I decided to stick the rock walls to the back panel using silicone.  This is why I did not shave the foam all the way down to the rock wall, I found it’s a little easier to get the silicone to stick to the back panel if there is no egg crate involved.


Once the piece is in place it will take about a day for the silicone to dry.
If you notice in the image below I had to wedge some rocks under the rock wall to make it stand up strait till the silicone dries.  Once it was dry I was able to remove the rock pieces.


After making several rock wall pieces in a row I began to glue them all to the wall.
Sometimes the wall would need to be propped up with something large.


In the image above you can clearly see each separate piece of rock wall from the lines in between them.  I decided to fill this area with some foam.  Before I got the hang of it I filled in a little bit too much and it expanded out farther than I wanted but I still like the filled in look better.


I made the last piece for the tank after I had all the others glued and in place because I figured this piece would need to be a little smaller.  It did need to be made smaller and I had to grind the dremel on a rock to make it fit. Also once I was sure everything was good and dried I went back through and cut off all the zip ties which were visible.  The foam held everything in place very nicely and it all feels very solid.  Below is the finished rock wall. Sorry about the horrible picture. Better pictures will come later once the tank has water!



Overall I think it turned out really nice and I’m excited to get the SPS glued onto my rock wall. It will be fun to watch them grow out and eventually hide the foam. I hope this article was helpful for when you begin aquascaping rock walls for a reef tank yourself!





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