# Do I need to seal "Great Stuff"



## GoneHuntin (Feb 1, 2011)

I am new here and going to make a 3d background out of eggcrate, great stuff. I was going to use the eggcrate as base then spray the great stuff then embed rock chunks into the foam. I was then planning to use some epoxy resin and sand to fill in the gaps. Question is do i need to seal the great stuff that doesnt not have rock or sand resin imbedded(ie the back of the background. It will not be sealed to the back of the aquarium as it is active aquarium. I was going to make it in 3 pieces and hang it. Thanks


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## Cognition (Oct 14, 2009)

You could use the spray pond sealant, I thank tetra-pond foam(maybe?) I'm fairly sure great-stuff(the yellow foam?) does have to be cured or sealed were as the pond foam doesn't.


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## bearwithfish (Dec 20, 2010)

i would seal it after it sits for atleast 48 hours. just to be sure.. my question (because i have been considering the same) is how to over come the floating power of the foam?


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## GoneHuntin (Feb 1, 2011)

thanks ....my plan is to embed river rock into it while still wet....i will put epoxy resin in the cracks and put sand on the epoxy while wet to fill in the cracks. I am hoping the rocks will help with the floating if not i am going to put a small footing on it as well so could just set the edge of some of my holey rock on it. What do i need to seal it with?


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## bearwithfish (Dec 20, 2010)

i would say epoxy or dry-lock ( i have read and seen great things with dry-lock) thanks for the idea i hope you post some pix !!!!!!!!!!!


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## gilberbt (Aug 1, 2009)

You can get Great Stuff for "Ponds and Stone" that is fish safe. http://greatstuff.dow.com/products/pond-and-stone/ I tried using it in a 3D background attempt similar to what you are talking about and didnt like how it came out it so I scrapped the project. It is black and cures with a glossly coat, however just note it will expand a ton and does not look as good if you need to trim it back (more of a foam look than glossy solid finish).

EDIT: Note since this is ment for fish applications it does not need to be sealed. However there are more proven ways to create 3D backgrounds with foam and drylock that may look better, I know mine didnt look that good but I also dont have any artistic ability so maybe that was my problem  .


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## GoneHuntin (Feb 1, 2011)

ya it does expand a lot...I have used it for its actual use of filling in cracks when i was building some other stuff....most recently a box blind. I am going to try to go slow and do small sections at a time so as not to get it to thick as it will be going into a 55 gallon so I dont want to take up too much space.


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## gilberbt (Aug 1, 2009)

Good luck on it, you have got me thinking again to try another approach like what you mentioned with great stuff stone and egg crate. Possibly if you could get enough stone on it and minimal great stuff you may be able to make one that doesnÃ¢â‚¬â„¢t float to add a 3D background to and existing tank setup where you donÃ¢â‚¬â„¢t have to silicon it to the back so it does not have to be 100% permanent.

I might tinker with that in the next few weeks if I have any free time. I would be interested to see how yours turns out, so post some pictures when you get some updates on it.


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## kriskm (Dec 1, 2009)

This is a cool 2 tank system that uses the reef technique you're talking about:
http://www.plantedtank.net/forums/tank- ... ridge.html


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