Is Expanding Foam Safe?

[Hakai]

So I'm trying to put up this cork tile background in my 10gal tank using some silicon glue. It's 12"x18" so I'm laying it horizontally on the back wall and the 10gal is 20" long leaving about an inch of space on either end. I'm worried about feeders getting caught behind it as for some reason they're all concaved and I'm wondering if I could just block that area off with some expanding foam. Is it toxic? How does it handle humidity? If I shouldn't do this, do I have any other options? The 3rd pic is the area I would be putting the foam.

 

[ferretinmyshoes]

I used expanding foam in my Pygmy tanks. It handles the humidity very well, but I covered it in black silicone and then stuck bark and coco fiber and stuff into the silicone while wet so when it dried it looked very naturalistic. It's messy but super easy if you want to go for a more natural look.

 

[Hakai]

I used expanding foam in my Pygmy tanks. It handles the humidity very well, but I covered it in black silicone and then stuck bark and coco fiber and stuff into the silicone while wet so when it dried it looked very naturalistic. It's messy but super easy if you want to go for a more natural look.

Awesome, you answered my next question. I didn't want it to look ugly. Thank you so much for the hasty reply! Can't wait to get started on this tomorrow! Setting up is so much fun!