# DIY Faux Rock background- looks awesome!



## redchigh

Thought this might be useful- I plan on doing it when I have a bigger tank... I think mine will look cooler. 

*Supplies needed:*


Quickcrete Blended Mason Mix
Concrete color mixes (black/red/buff)
Large Tubes of Silicone – Doors and Windows Silicone without any Bio-guard or additives
Rigid Styrofoam Boards – 1/2″ thick and 2″ thick
Disposable paint brushes (10-20)
West Marine Epoxy Mix – 105 Resin & 207 Hardener (I’ll explain more later)
West Marine pump kit (this makes measuring the resin and hardener really easy)
Box of Disposable gloves or a heavy pair of rubber gloves.
Plastic containers for mixing concrete and for mixing epoxy – He used some old plastic juice containers.
 *Tools Needed:*



Large Knife
Heated cutting tool (optional – helps)
Caulking Gun
Straight edge
Ruler
Thick point marker (Sharpie)



Click the pic for the link.


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## aunt kymmie

That looks awesome!!


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## LisaC144

So cool! Do it on one of the new tanks you might be getting ;-)


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## redchigh

Hmm. I might just do that. (I'd create a few holes in the "shelves" so I can drop in some potted dwarf baby tears, cover it with moss (java and either christmas or flame moss) and probably silicone some sand onto it post production with silicon rather than paint it.


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## keno

redchigh;

I saw that you found my article on the faux stone backgrounds.

I wanted to let you know that I have been working on some updates to the process and I thought you may be interested in them.

I have found that if you use quikrete concrete acrylic fortifier instead of water it makes for a much better bond of the concrete to the styrofoam. I also found a small metal and plastic sanding tool that will rough up the surface of the styrofoam which also allows the concrete mix with acrylic fortifier to stick really well. This way you can skip the first step of the concrete process where you would have had to make a thin mix of the concrete and water and paint it on. I mix the concrete and acrylic fortifier together to get a thin peanut butter consistency. I then paint it on the styrofoam. I am pretty aggressive on this first step to really get the concrete on the styrofoam. A little mix goes a long way. This process is much better than using water. I found the acrylic fortifier at my local Lowes store.

I like your idea on adding the plant pockets. I am currently building a faux stone background for my 200 gallon aquarium and I was doing the same with the plant pockets. I am also making individual faux stones for my 200 gallon aquarium. I felt this would give it a more real stone look. Each stone will be siliconed to the one below and to the back of the aquarium.

I added a picture of one of the faux stones with just one coat of the concrete and acrylic fortifier mix.


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## trukgirl

Wayyyy too cool. I am so fed up with the picture backgrounds.

I think this may go on the Honey-Do list, LOL!!


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## redchigh

Wow, keno. Didn't think the master would stop by. lol.

I love your whole blog, figured this was one of the best things on there to bring people over to look around. 

PM me... Have a question to ask you.

That new rock looks way better.  Plus, the acrylic ight make the concrete a little less porous, which was one of my big concerns.

I had another idea, of mixing colored sand (black, red, brown, etc) into different batches of concrete, and then using all four colors in the final product by only blending the edges...

Making different rocks to stack as a bg... interesting. Wouldn't just carving the bg out of styrofoam look the same though?(like, instead of adding the rocks individually like the first one, just dig grooves into it about halfway through the styrofoam, and oversanding some of the protrusions so they're not all even.

I dunno if it would be worth the extra work though now that I think about it.

I was thinking about dwarf baby tears, and thats what gave me the idea for a slot to drop plant pots in... (I have a low-tech tank, and I was thinking "How can I move the baby tears up closer to the light?" when I stumbled onto your site. I dont remember what link brought me to your site to begin with... but I'm glad I was bored that day and decided to explore.


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## keno

To answer your question about making individual stones versus just carving a larger piece.

Yes, you can put together pieces of styrofoam to get a thicker piece and then just carve the look into the styrofoam. I can and I can't do this for my 200 gallon aquarium. It is an acrylic tank with a sealed top an only two small openings. So I can't get a big piece of foam into the aquarium. I could build smaller sections and put them in, but I think the individual stones will give it a more realistic look. A lot more work, but you also have the ability to change things up. When you are building it you can move stones around to see if you like the layout better.

I included a couple of shots of my background for my 200 gallon. I made a cardboard template of my 200 gallon to make it easier to build the background. The height needs to go to the top of the cardboard. I have been thinking that I may put in some spacers between the stones to separate them slightly and allow the stones to stand out more.


Look I already have a "cat-fish" that moved in.... he also gives you a sense of scale.....


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## redchigh

Nice. I like it.

I'm sure you know, the more caves the better.  Look real nice with some mosses and epiphytes on the rock.

Can't wait to see it completed.


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## teddyzaper

omg you have inspired me to make one for my 55 gallon. my only question is price? how much for all of it and expecialy what type of foam do i use?


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## keno

teddyzapper;

Here is a breakdown on the material cost. Remember the styrofoam and the mortar go a long way. You can make several backgrounds with them. The most expensive items are the epoxy resin and hardener. Since the resin and the hardener are matched in size. So if you purchase one can of the resin you will need one can of the hardener. I used 1.5 cans of each between my 20 and 55 gallon backgrounds. For my 200 gallon aquarium I would have to estimate that I will use 2-3 cans of each. I believe the benefit of sealing the concrete outweighs the cost. The good news is that I will not need to purchase the mortar, concrete colorants, pump kit, and gloves. I do have some of the styrofoam left over. I may need more of the 2" size.

I may go ahead and get a heavy duty heated cutting knife. The knife costs around $70.00. The heated knife will eliminate the styrofoam dust that gets and sticks to everything. I did find that by cutting or hacking the stone pieces inside of a box helped to control the styrofoam waste.

Material List Cost (Total ~161.00):
2" styrofoam - 2' x 8' - $14.86
1/2" - 4'x8' - $17.72
10.1 oz. Clear Silicone I Window and Door $3.79
QUIKRETE 80 Lb. Pro Finish Blended Mortar Mix $5.25
QUIKRETE 10 Oz. Cement Color $5.17 x 3
Disposable paint brushes 15 for $8.97
West Marine 105 resin quart - $35.65
West Marine 207 hardener small can $34.97
West Marine Pump Kit - $13.99
Disposable gloves - $10.00


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## AaronCombs

I wonder how sand pits on the rocks would look.... 

IE make raised edges on some of pieces that stick out, in which you can place sand in it.

If I can I might try this later down the road and set this up.


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## redchigh

I think that would work cool.. shrimp would like it I bet.

Make sure they're the same size as a plant pot so if you don't like the sand you can take it out and throw a plant in it.


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## AaronCombs

yeah thats what i was going for, lol thanks for specifications encase others didn't catch on


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## Grimmjow

What do the West Marine 105 resin and West Marine 207 hardener do? and are they necessary? (i ask out of cheapness)


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## keno

Grimmjow;

The purpose of the epoxy (resin and hardener) is to seal the faux stones. The concrete or mortar mixes are made up from a number of materials, limestone being one of them, that will effect your water's pH levels. By sealing the stones in epoxy you will not have to worry about the faux stones affecting your water's chemistry.

I have read on the internet that others have not used the epoxy to seal their stones. What they claim is that they need to fill and drain their aquariums a number of times and in some cases wait weeks, until the water chemistry stays stable. 

I did not want to take a chance with my water's chemistry, so I decided that sealing the stone background would be the better way to go.


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## Grimmjow

Ah i see, thanks.

Im thinking about trying this out. Right before i saw that cat in that picture i was thinking my cat would be a problem with all the styrofoam since he ges crazy over it, but then i thought i should just let him tear it up a little or maybe just try it on one piece since the claw marks might end up looking like cracks and make it look more real.


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## keno

If you are going to try to make cracks, just remember the mortar mix is pretty thick, so you have to over exaggerate the crack. As you are applying the mortar mix you can also use a wooden tongue depressor to get some of the mortar mix out of the crack you created. I have found it a bit tough to make smaller cracks in the faux stones. Maybe before the mortar mix is completely dry you can try scratching it to see if that would work. I plan on trying that technique on my next set of stones.


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## TexasTanker

keno said:


> If you are going to try to make cracks, just remember the mortar mix is pretty thick, so you have to over exaggerate the crack. As you are applying the mortar mix you can also use a wooden tongue depressor to get some of the mortar mix out of the crack you created. I have found it a bit tough to make smaller cracks in the faux stones. Maybe before the mortar mix is completely dry you can try scratching it to see if that would work. I plan on trying that technique on my next set of stones.


A note on "etching" the mortar. I pretty much grew up on a construction site, namely my childhood home. The entire inside was cement stucco. My dad didn't do anything little and as such I learned a lot of techniques to add texture, color, and "flair." 

In stucco there are traditionally 3 coats of masonry that go over the lath. The bottom coat is scratch coat. Much like the OP's instructions, it is a thin rough coat that allows the heavier second coat to adhere. After the scratch has set, the brown coat is added. This is a much thicker coat. This is where much of the shape is added. In my house, we carved stones, designs, even a dragon and castle, into the brown coat. This can be tricky since it sets up somewhat quickly and carving at it at different stages changes the texture of the design.

For years of experimentation and tool buying the most effective and versatile tools we used were a fork, knife, and spoon. They're riddled with different angles, edges and shaped that lend to pretty much any design you could want to make. I became proficient at the process very young and eventually took over the carving and designs. ( much of this was done on scaffolding at odd angles in high humidity) Anyhow, my experience taught me three things. Go in stages. Do a rough carve or shape on everything first, then do a second refinement, and finally tweak what ever you need to. This allows the texture of each to remain similar. 

This project is not a house and is much smaller in scale so much of this can be ignored, I still dabble in playing with cement and I still rely solely on eating utensils. Another trick to adhering the the cement to the foam would simply be elmer's glue. If you do a medium coat over the foam and allow it to begin drying before adding cement, the glue will seep into the cement and the foam. NOTE, if you mix it with the cement it may lend to discoloration. 

Because the cement will be sealed with epoxy, you can also use powdered RIT dye to color it. This is a really neat effect for making green, blue, brown or red. Remember your color wheel and go a shade darker than you want. You can add in bits until you achieve the shade you want. One small box was usually enough for a wheel barrow of mud, so a little does go a long way.

Next time I mix up a batch I'll scratch up some samples of some designs. Wow... I got pretty wordy, sorry.


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## keno

TexasTanker;

Thanks for all the insight. I can see a life time of experience is a great thing.

I have found that roughing up the surface of the styrofoam and using the acrylic fortifier along with a good stiff brush does a great job of getting the mortar mix to stick to the foam. You need to remove all of the shine from the foam. It makes a mess, and it's good to have the shop vac handy.

Thanks again for you insight....


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