[toffee]

I am wondering what would be the best glue to use if one wants to glue foam to rocks. Silicon or some other glue?

Thanks for helping.

 

[Mcdaphnia]

I use the waterfall foam to glue rocks to almost anything. It's designed for that, and fish safe.
http://www.ponddepot.com/blacwatfoam.html
Since it's black, you don't have the problem with silicone and other glues of looking really nasty if a little shows here and there. You can even use the foam to cover up spots where the styro shows through and to fill in gaps where fish could be trapped and be hard to keep clean.

 

[greenbirds]

Gorilla Glue claims to adhere to rock and foam. As a test I glued a heavy piece of granite slate to a piece of styrofoam, and it holds to the point where trying to separate them makes the styrofoam rip apart from within itself rather than the foam/rock interface, so that's good enough for me :thumb:. I have not tested it in water yet, but Gorilla Glue claims to be 100% waterproof. I am preparing to line the back of a large tank with slate rock this way -- slate to styrofoam with Gorilla Glue, styrofoam to glass with silicone. Will let you know how it goes in the next few days.

 

[toffee]

Gorilla Glue claims to adhere to rock and foam. As a test I glued a heavy piece of granite slate to a piece of styrofoam, and it holds to the point where trying to separate them makes the styrofoam rip apart from within itself rather than the foam/rock interface, so that's good enough for me :thumb:. I have not tested it in water yet, but Gorilla Glue claims to be 100% waterproof. I am preparing to line the back of a large tank with slate rock this way -- slate to styrofoam with Gorilla Glue, styrofoam to glass with silicone. Will let you know how it goes in the next few days.

is gorilla glue fish safe?

 

[Mcdaphnia]

is gorilla glue fish safe?

The manufacturer claims their other product, Ultimate Glue, is, after it has cured. I didn't ask about Gorilla Glue. I'd be sure to rinse it before use, and I plan to use the Ultimate Glue for small jobs because it would be convenient and I might be able to fix small broken parts like on filters etc. For more extensive jobs I will still use the waterfall foam. The thing is once you open the waterfall foam, you have to use it all in a short period because it does not last long after being opened.

 

[R-DUB]

I agree with Greenbird-- use Gorilla Glue. After it is cured it is a hard plastic type product. Almost like Great-Stuff but harder. As far as fish safe all I can say is that I used several test pieces to see if my dry-lok worked. They all had G-G on them and no adverse affects at all. I did not contact the manufacturer good luck!

 

[greenbirds]

Supposedly is fish-safe:

http://cichlid-forum.com/phpBB/viewtopic.php?t=118325