DIY - Aquarium Background

Supply List:

• �" Thick sheets of Styrofoam
• Styrofoam balls from the craft store (optional)
• Any Styrofoam from electronics packaging (optional)
• 1 Can of "Great Stuff" expanding liquid foam (optional)
• Tubes of GE Silicone I and a caulk gun
• Razor knife
• T-square or straight edge
• Tape measure and marker
• Rags
• Rubbing Alcohol
• Sand Paper
• Old 2" paint brush
• Concrete pigment in black and brown
• 1 - 1� bags of Quickcrete Quickwall
• 1 40 lb bag of rock salt (for water softeners)
• Spray bottle

Step 1: Cleaning out your tank

Empty the contents of your tank and drain out all of the water. I used a wet dry vac to get out every last bit of water and gravel. Wash the empty tank with mild bleach water to get rid of the old gunk. Wipe all of the glass that will get the background with rubbing alcohol and a clean rag. Make sure your tank is dry. In my case, eighty percent of my sides glass will get covered up with the background as well as the back of the aquarium. You get one chance at this project so do it right the first time.

Step 2: Building your Styrofoam structure

Since I built my tank into a wall, I had to do this project in the vertical. Measure the inside of your tank and begin to layout the pieces that will cover the back of your tank. I covered the entire back and sides with �" thick Styrofoam as a base. You can score your pieces with the razor knife and straight edge and then snap them apart, or cut all the way through. Apply liberal amounts of silicone to your pieces as you begin to lay them onto the back of the aquarium. Press every square inch of the pieces firmly to the glass.

Silicone Pattern

After you get your first "course" of Styrofoam laid in, you can begin to create your levels. I didn't want to fuss with hiding my aquarium hardware behind the background, so I had to plan where they would go. I needed to leave enough space for my three filter tubes, so I only left �" of Styrofoam in the places where the tubes would go. I planned for my heaters to go in a 2" space on the front sides of my aquarium, so I made sure to leave that space clear. I also mounted my powerheads there.

Be sure to seal all of the join seams that come in contact with the glass. They are marked in red below. Even though I sealed my seams, I still got water behind the Styrofoam.

I basically stepped my levels from top to bottom with the whole back and sides at �", 2/3 of it at 1" thick and 1/3 of it at 1�" thick. Start building detail by cutting or breaking shapes and layering them forward. It's OK to just break the Styrofoam. You're going to cover all of this up with concrete anyway. Be sure to put enough silicone to hold the pieces in place. Next fill in gaps and start to smooth things out with your can of "Great Stuff". Let the silicone and "Great Stuff" dry for 24 hours. After the "Great Stuff" has hardened, take some sand paper and rough up it's smooth surface, so the concrete will stick to it. At this point you can also use a propane torch to melt some of the surfaces together. Be careful though, Styrofoam is very flammable. I burned a few hole through my background and had to fill them in! Be sure to vacuum out all of the loose Styrofoam pieces, dust and debris before applying your concrete.

Add "Great Stuff" to smooth out your structure

Step 3: Adding your first layer of concrete

This is where we have fun. Quickcrete Quickwall is a white concrete mix that has glass fibers in it. Leave them in. Why? Because they add strength and character to your structure. When your done, it will look as though your wall already has growth on it. It will create a structure for bacteria and algae to anchor on as well. OK, mix your first batch of Quickwall. Make it loose and soupy and add color if you want to test it's effect. Brush it on with your old 2" paint brush. Let this dry for 24 hours. I hated the color, so I knew what to do for my 2nd and final coat.

Thin layer of brushed on concrete

Step 4: Adding your 2nd and final layer of concrete

Mix your concrete thick. Add color if you wish. I did the final thick coat of concrete in one session in three different sections. You will need a lot of concrete here, so mix plenty. You will use your hands here. If you are smart, unlike me, you will wear dish gloves. My hands dried out out from the concrete. I started from the bottom right and worked my way up and left. Start filling in crevasses and smoothing out your jagged rock formations with your hands. When you get 1/3 done, stop and grab a dish of water with pigment and your 2" paint brush. Now, start stippling from the bottom and work your way up. The stippling effect will jab your concrete into cracks and crevasses and will also create a realistic rock texture. I didn't want my finished product to look smooth. Feel free to have a few pans of different hues and colors of pigments to stipple in color where shadows are etc. I also took my brush and spattered the pigment on and went over the surface with a spray bottle of water (see below). It will create a dripping effect and the pigment will fall naturally around shadow areas and low spots.

This is stippling! Tap, tap and tap!

It looks like the wall is dripping

When you are complete with all of the concrete coverage, take your brush and smooth your three seams at the bottom and two sides.

Step 5: Curing the concrete

We need to sprits the concrete with water for the next several days while it dries. This will add strength to your structure. You need to do this step often (at least 6 times a day if possible). Make sure you are not curing in full sun or very hot conditions. These conditions can make the concrete cure too fast and make it crack! After about three days of curing, we can fill the tank.

Start filling the tank with luke warm water. I slowly added about 20 pounds of salt while the tank filled with water. Adding salt will speed the curing process! If you have any, throw in your driftwood as well. The salt will help leach out some of the tannins in the wood. After the tank was filled with salt water, I added two powerheads to the front of the glass to circulate the water. Soak and circulate for at least three days.

Soak in saltwater for at least three days.

Soak your driftwood too!

Step 6: Flushing with fresh water

OK, 3 days have gone by and the concrete should be very hard as a rock. But, we aren't done yet. We need to drain the salt water and flush it with fresh water. I emptied the tank and refilled it with fresh water and circulated with the powerheads for another 3 days. After the three days, I repeated the process two more times, three days each time.

Step 7: Finishing up the project

The tank is fully cured and I am ready to complete the project. I added eggcrate to the exposed glass bottom of my tank and then added my new sand substrate. I placed my rocks and fake plants and then began filling up my tank for the last time. I turned on the heaters and started my filters. I let the tank go a few days and then started my cycle. Now go and DO THIS! You will be amazed at how easy it really is.

The tank will remain cloudy for awhile

Here is the completed tank fully cycled and with fish. I love my tank now. It is a show piece that my family and friends enjoy. □