What to use to fill in gap between 2 foam rock wall sheets?

Charles4400 · Oct 2, 2017

Had to make a separate smaller foam rock wall piece for my back wall so I could get it in the tank. (Eggcrate with dry rock and pond foam).

I'd like to fill the gap between the 2 pieces to make it look like one piece (will be putting epoxy and sand over all foam and filled gap).

What material would you use to fill the gap? Would silicone work? Would that stick to foam and epoxy stick to the silicome?

cilyjr · Oct 2, 2017

Why not shoot a bead of foam?

Charles4400 · Oct 2, 2017

I was trying to avoid that since Id be wasting the whole can of foam on just using it on 1 strip. I dont believe the cans can be saved for later use.

Also foam is messy as hell, especially when i would need to pat it down so it doesnt bubble up so much, and I would rather have all the foam stuff done outside the tank.

If I have to I will end up doing that, just hoped there was a cleaner, less messy and wasteful way to go about it.

JoshH · Oct 3, 2017

Never used pond foam before but if it's similar to spray foam insulation all you need to do to preserve the can is clean the tube and head of the can with acetone. Used to do that all the time insulating homes and worked like a charm. you do have to clean it shortly after use or its a real pain to do but still not impossible if you let it sit for a while.

Charles4400 · Oct 3, 2017

Thanks, Ill try that. I always thought these cans were a one shot deal, but if it can be saved even better!

Yes I think will use the foam to fill the gap, will probaby blend better as well.

JoshH · Oct 3, 2017

I think you will get the best results with using the foam. What type of foam is it exactly? You should be sure that the acetone would work, it should but I can't be 100% sure cause I've never used that particular foam product. Look on the side of the can and see what it suggests to clean up with. Or if you have some extra foam bits laying around pour a little acetone on them.

Charles4400 · Oct 4, 2017

I'm using this:
https://www.amazon.com/Beckett-Corp...8&qid=1507101311&sr=8-1&keywords=beckett+foam

I might have some acetone laying around, if not I'll try mineral spirits which I should have laying around. Worst case scenario I'll waste a can just for the fill, I suppose $17 isn't much compared to the thousands spent on this hobby. Just seems a shame to waste it if it comes that.

JoshH · Oct 4, 2017

Reading the SDS you should be able to save it if when you're all done you immediately wash with acetone but you can't let it dry. Info in line 6. But I agree in the end its best to use the same material you already have even if you have to waste it. On a side note, we're going to have to see pictures of this fun project!