# Fake rock background



## Sterving (Dec 23, 2004)

I am a bit weary of the Great Stuff foam being exposed to water, even if it is covered with grout/paint. Most importantly, Great Stuff foam is cellulose based and grout/paint is not 100% waterproof so the water WILL get to the foam. That means that it will eventually disintegrate due to bacteria and your entire rockscape will come off loose from the glass and foul up the water.

Then there is a question of chemicals in foam/grout/paint. As you already know, the mortar is giving you grief by leaching minerals into the water and messing up with pH.

A much safer way to build a rockscape background would be to use hard styrofoam. Glue up enough sheets to get to desired height and then carve out the scape. You can use a rotary tool or even an exacto knife to do that. Then paint everything with a mix of sand and either aquarium-safe epoxy or silicone. The epoxy will become hard when cured while silicone will stay flexible. I am leaning toward silicone as it will enable me to attach stuff to the scape, like some sort of clip/holder to help annubias.

Search the forum for more info on DIY rock backgrounds. IMO, Great Stuff foam + mortar in the tank = TROUBLE :eek5:


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## zachxbass (Jul 6, 2008)

I do understand what you're saying... but as far as the great stuff breaking down, i don't think that will be a problem... Although it is toxic before it cures, once dried i believe it is chemically almost identical to any other polystyrene foam.(i'm no chemist though) I have read on dendroboard about people using it in dart frog habitats, and paludariums where it is constantly wet/ submerged, for years, with no signs of breaking down. Now, i'm no scientist so i very well could be wrong. As far as i can tell the mortar is a much bigger risk than the foam is... But, once the mortar is completely cured, (which i know could take a very long time) it should be inert. The 55 gallon paludarium i have has a running creek that is made of great stuff and covered in the same mortar/ acrylic paint. It has had water running in it for around 6 months now, and the water parameters are stable and fine. The betta i have has lived in there for around 3 months now and is healthy and active....

I hope it doesn't appear like i am dismissing your advise, because i'm not. It's just that from my reading, and my experiences, great stuff should be just as non-toxic as other styrofoam. The mortar on the other hand, could be a problem.... I believe once it is cured completely it should be fine, but like i said i could be wrong.

Thanks for the response though, as it does give me some more research to do, and things to think about. 

I'll continue to monitor that water in this tank and hopefully the pH will stabilize eventually... worst case scenario, i can rip the background out and just spray paint over the pieces i can't get off (there's alot of silicone holding it in place).... which won't look as good but would at least leave it with a little texture, instead of just flat.


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## zachxbass (Jul 6, 2008)

oh, one other thing i thought of... IF i can't get the cement to neutralize, and stop leaching... I suppose i could coat the whole thing in clear epoxy, basically sealing the whole thing... but i'm not sure if it will make it look too "shiny" once submerged.
I guess i'll just have to wait and see what happens.


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## Sterving (Dec 23, 2004)

zachxbass said:


> oh, one other thing i thought of... IF i can't get the cement to neutralize, and stop leaching... I suppose i could coat the whole thing in clear epoxy, basically sealing the whole thing... but i'm not sure if it will make it look too "shiny" once submerged.


Mix some sand of various size into epoxy to make it look more natural and elminate gloss.


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## OverStocked (May 26, 2007)

Great STuff has been used in backgrounds at cichlid forum for a long time with no ill effects. It is insanely bouyant though and you will struggle to sink it, thus I recomend using it in the tank and it will adhere like no other product.


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## zachxbass (Jul 6, 2008)

yeah, i convered the back of the tank with silicone, then let that dry, then added the GS... that's what people in the dart frog hobby do, because the foam sticks to silicone very well. It will stick to glass, but not nearly as well as it does to silicone.

I have still been leaving the tank full of water, and changing it nightly.... it is still buffering, but not at the rate that it was.... one question about this.

So, there are rocks, materials, etc... that buffer in a way that it RAISES ph.
Is there anything similar that could be used to counteract that in an effective way? I think i have heard of people using peat in their substrate, and (i think) even in there filter. It would probably be way too hard to balance this out, and may not work at all... but thought i would ask.

i read on some cichlid forums, and it seems like this method is used by at least a few on there. and i don't think they all coat the cement with epoxy... but most still do.

I think for the most part there is still no verdict as to wether the cement will cure completely enough to be safe... but i'm almost positive that it will, and has been done. So, i'm going to continue with this, and hopefully prove it will work, as i think this method can make some amazing looking backgrounds.


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## DiscusIt'sWhats4DinneR (Apr 25, 2008)

i would love to see some pics of this.

i would also like to make my own background, epoxy/sand coated and with lots of little crevasses to shove anubias/ferns and moss to grow. it might not even be a bad idea to find a way to attatch a piece of driftwood so that it comes out of the background too, like roots. too cool.


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## zachxbass (Jul 6, 2008)

DiscusIt'sWhats4DinneR said:


> i would love to see some pics of this.
> 
> i would also like to make my own background, epoxy/sand coated and with lots of little crevasses to shove anubias/ferns and moss to grow. it might not even be a bad idea to find a way to attatch a piece of driftwood so that it comes out of the background too, like roots. too cool.


Sorry, still haven't taken pics.. I just got a 55 gallon so that's been getting more attention.

As far as the driftwood, all you have to do is us silicone/ great stuff to basically glue the driftwood to the background.... the 55 paludarium i have has 2 large pieces, and several smaller ones, "glued" into the background... seems to work fine, and i would find it very dificult to remove them.
This one also has several pockets in the foam where i have plants growing... i'd imagine it would work about the same under water. You can even put little pots in the foam before it dries, and foam around them.... leaving perfect places for plants to go. 

I think the only downside to this method is the grout/ mortar, leaching and buffering your water... 

You could easily just put paint directly on the foam to prevent this... but in my opinion it doesn't look as good. (the foam doesn't have to be sealed, and doesn't have any adverse effects on fish by itself) At least not my betta.. although they are really hardy anyways.


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