# Making Your Own Foam Rocks For Rock Dwelling Africans



## Larry1981 (Feb 3, 2009)

*Please do this at your own risk results may vary!!!!!*

*Supplies needed :*

*6 16oz cans of Great Stuff (Gap and Crack)$3.49 each

10lbs of Quikcrete Cement (Small Bucket) $12.00

50lbs of Quikcrete Fast Setting Concrete $5.97

Plexiglass was free from a friend not sure on the cost?

2 50lbs bags of Play Sand $3.95 each ( for substrate. I had a bunch left over because the structures covered a lot of the bottom) *

*All of these products were purchased at Home Depot.*

*
Note :*_ The Spray foam is really sticky. If it gets on you and if you let it cure it is next to impossible to get off (just like super glue it has to wear off naturally). If it is uncured the say on the can to use Aci-tone. Didnâ€™t work for me though. LOL! _

*
"I assume its safe for fish because I used this product following directions for curing".*

Before you begin get a smooth surface (used a piece of scrap plexiglass) mist with a lot of water helps when removing the foam from the glass ( This is for making base for the structure it gives you that flat surface for the structure to sit level in the aquarium).

Lay out some play sand in a big container and apply the foam directly on top of it.

I just figure this out yesterday 02/05/2009 while doing a little experimenting with the foam and sand (this gave the rest of the foam rocks a 3-D look all the way round).

Also did another experiment with the sand and the foam by dusting the uncured foam with the sand, this gave it a rough surface for the cement or concrete to adhere to.

Before you cement or concrete be sure to get the remaining sand off the foam, so the concrete or cement can bond to the surface.

What you do is after you get the shape want, you mist with a lot of *"water speeds curing and seals the foam(1 - 2 hours)"*.

I made over 30 individual foam rocks this way. After you made as many rocks as you need (you may need a lot if you plan to run the length and height of the aquarium).

Start carving out the caves.I used my really long thumbnail to carve out caves in the foam.

Then I stacked them the way I wanted them, I then took them down to begin gluing process.

With the same Great Stuff Gap and Crack I used to make the rocks(pay attention to the size of the aquarium and the braces of the aquarium, so that you can get the structures in the aquarium).

Now comes the fun part using the spray foam as glue. I laid out 4 (varied sizes) of the foam rock on a flat level surface, I stacked these foam rocks like pyramid using the spray foam on each side of the rock where it meets the rock below it ( I did this process on the first structure).

Just keep stacking and be creative and use your imagination its time consuming and fun (I have had a lot of time because I got hurt at work and needed something to do to keep me sane) you will be surprised how natural it looks once the cement and concrete goes on.

I mixed the cement 4 parts sand and One part Cement (I used cement on the first structure I have already completed).

Be sure to keep the cement wet while curing to prevent cracks (I didnâ€™t keep mine wet enough and had to do some crack repairs), but you don't have to keep the cement wet if you are using Acrylic Fortifier ( I didn't use this because I did want to add too many Chemicals to the process).

I Just started another rock structure yesterday 02/05/2009 using the same foam, but this time instead of cement I'll be using Quikcrete fast setting Concrete (Bag says it sets in 20-40min)

The structure that is completed is 3â€™ long x 12"wide x 13" high

The second Structure is waiting for the concrete process is 2.5' long x 17.2" wide x 19" high

Iâ€™m sure there will be questions, concerns, and comments. Iâ€™ll be monitoring this post from time to time to address these issues.

*Picture of the process as wells as the finished structures and the structures in the aquarium coming soon!*


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## JWerner2 (Jul 7, 2008)

Awesome! Cant wait to see the pics. Maybe request this to be put in the DIY section o f the library.


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## ilikebeer1985 (Dec 21, 2007)

i have been thinking of this forever but didnt have the guts to try it.
cant wait to see it good [email protected]


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## Mcdaphnia (Dec 16, 2003)

I tried it years ago when Great Stuff first came out. Great Stuff continues to expand after it appears to be dry and cured. It can crack glass, cast off any coating or paint applied too soon, and may not be fish and plant safe. Since then, Great Stuff has come out with a different version that does not expand with as much pressure, so it won't crack glass, or chuck off a thick rigid coating that can hold it in, but it may not be fish safe. I got a couple free 75's that someone tried the Great Stuff backgrounds in. I could tell they didn't tip the tanks on their back because the foam sagged as it dried and they had to add a new layer on top. Both tanks have a cracked glass panel.

I use pond waterfall foam that is a little more expensive but suited to use with fish and plants. It is designed to stick better to rocks, glass, and plastic. It is almost black so it jars the eye much less if a bit of happens to show through the surface treament. It will hold up without the treatment since it develops a tough "skin". Exposed Great Stuff will turn orange and then crumble into particles.


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## xwolfiex (Feb 3, 2009)

great stuff now has a pond foam as well...

http://building.dow.com/na/en/products/ ... dstone.htm


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## JWerner2 (Jul 7, 2008)

Mcdaphnia said:


> I tried it years ago when Great Stuff first came out. Great Stuff continues to expand after it appears to be dry and cured. It can crack glass, cast off any coating or paint applied too soon, and may not be fish and plant safe. Since then, Great Stuff has come out with a different version that does not expand with as much pressure, so it won't crack glass, or chuck off a thick rigid coating that can hold it in, but it may not be fish safe. I got a couple free 75's that someone tried the Great Stuff backgrounds in. I could tell they didn't tip the tanks on their back because the foam sagged as it dried and they had to add a new layer on top. Both tanks have a cracked glass panel.
> 
> I use pond waterfall foam that is a little more expensive but suited to use with fish and plants. It is designed to stick better to rocks, glass, and plastic. It is almost black so it jars the eye much less if a bit of happens to show through the surface treament. It will hold up without the treatment since it develops a tough "skin". Exposed Great Stuff will turn orange and then crumble into particles.


If I am ever using it for terrarium back grounds I make sure to put it on some foam sheets from a craft store. Then after it dries I work with it.


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## Mcdaphnia (Dec 16, 2003)

JWerner2 said:


> If I am ever using it for terrarium back grounds I make sure to put it on some foam sheets from a craft store. Then after it dries I work with it.


 Great idea on what to do with what's left in the can since it won't keep after the can is started. I usually set up some extra projects and do as many as the can lasts for, but this would be great for when you don't have many optional projects ready.


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## R-DUB (Jun 3, 2007)

Please post some pics!!! :thumb:


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## Larry1981 (Feb 3, 2009)

I did not use the foam directly in the aquarium that what the Plexiglass is for. I used great stuff Gap and crack because it doesn't expand that much like the great stuff used for windows.


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## JWerner2 (Jul 7, 2008)

:x Pics!

 Please?


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## ilikebeer1985 (Dec 21, 2007)

we definately need pics!


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## Larry1981 (Feb 3, 2009)

The foam rocks I created need more weight to them they float. I guess I need more concrete.LOL!

Another 80lbs should do the trick.LOL!


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## Larry1981 (Feb 3, 2009)

*Mcdaphnia*


> Great idea on what to do with what's left in the can since it won't keep after the can is started.


Great Stuff will keep in the can after you have used some as long as it is allowed to seal itself.

Meaning you should keep the strawl attached....


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## ilikebeer1985 (Dec 21, 2007)

did we forget about this thread>????


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## kelownacichlids (Mar 3, 2009)

Foam rocks float, I don't think you could add enough concrete to make them stay down. I tried, won't work  My next attempt I think I will use acetone to dissolve the foam in the rocks after I get a good concrete shell and then sink them after letting them fill with water. I feel that they would be really light that way and you could get a really nice pile without too much stress on the tank. Just a guess though, I haven't tried it yet.


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## under_control (Jan 9, 2008)

That seems like a lot of work, considering you could just use ROCKS. You can put more rocks in your tank than it can hold.


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