Packing foam

[green plant]

I have this foam from machine storage boxes. It is pretty compack and can be easily slided off with pen knife. Has anyone used those compact packing foam (not styrofoam) in planted tank?

Is it safe for fish and plant?
What are the things that I need to look out for?

[green palette]

Hi Bro,
maybe you can describe what you intend to do with the foam first?

[green plant]

Hi Bro,
maybe you can describe what you intend to do with the foam first?

As it is compact, my intension is to make used of it as a divider to hold the sand and create some sort of "river".

[Blaze88]

erm wont the foam float up to the surface? why not just use a hard plastic devider or those overhead projector plastics to hold the sand, their transparent aswell. and well, non biodegradable. =P