Hey guys

I was happily going along with my plan to build the land area of my terrarium and had a spanner thrown in the works. I wanted to use expanding foam covered in silicon and eco earth. Some have said that eco earth would rot if always submereged in water? Would this be ok to do or will it rot?

Any advice or experience in this area would be massively appreciated as I want to start my land area asap.

Many thanks
Jon.