Rocks, Foam, Silicone

[fishwatcher]

I am wondering if it is safe to silicone a piece of (pink) polystyrene foam to the bottom of rocks I'll be adding to my tanks, to help keep any sharp edges from busting the tank. One is freshwater and one will be saltwater. I've read where one person said foam is good to use, but it was from a post a year or 2 ago and I want to make sure it still is ok.
Thanks!

 

[rdd1952]

Generally there should be enough cushion from the substrate to prevent any problems. Also, unless the rock is large, a piece of foam large enough to really cover the rock could possibly make the rock prone to turning over as the foam tries to float to the top. If you do try it, just make sure the silicone is safe for aquariums.

 

[fishwatcher]

From what I've read it is safer to have the rock sitting on the bottom of the tank, then add the substrate, particularly when you'll have sand sifters in the tank (this will be for a shellie tank). This is what got me to thinking that a sharp corner could crack the glass. Maybe if I stay with tufa and lace or lava rock and put just a fine layer of sand underneath it would be ok?

 

[promithius]

yes, always sit large rocks and wood directly on the glass.

As to the foam, you shouldnt need it. so long as the rocks are stable they should be fine

 

[fishwatcher]

ok, thanks!