styrofoam and cement background

[nljohnson1960]

I want to start constructing a styro and cement background with a sandfall.
My problem is I have the 55 Gal already setup for many years. Fully stocked with live fish. Is there anything I can use to mount the background to the glass in an active tank that will cure underwater without harming my fish???

I can't see restarting my tank for this project?

[Aiken Drum]

Best i can find.

https://www.aquariumadvice.com/forum...nd-156441.html

[evil Nick]

Strong magnets?

[nljohnson1960]

I will test it tonight and see if it works through the thick glass of my 55 Gallon Tank.
I've used them before for other applications at work.