Bioactive terrarium for Giant African Land Snail: what substrate? Size?

[RufusLoacker]

As the title suggest, I want to make a bioactive terrarium for my two GALS (Lissachatina reticulata) with a couple of plants, like spiderplant/fern/pothos/something else that's safe for snails, and I was wondering what would be the best substrate for the plants.

I noticed that snails really like coco coir, rather than peat, but I'm wondering if it's good for plants.

Additional question: I already have an aquarium that's 100x30x40h, and I want to divide it in two to put a single snail in each half to minimize egg laying.
They're currently still little (2 months old), and I was wondering if the tank is too small.

Thanks in advance!

 

[Glorfindel]

Very Large Hermaphrodites, can breed like crazy.
Restricted in U.S. , considered an Invasive Species.
I realize you and snail live in Italy, where it's legal.
As for substrate, make sure it's 100% Organic not treated with Chemicals.
Cool looking Mollusk, enjoy.

 

[RufusLoacker]

Very Large Hermaphrodites, can breed like crazy.
Restricted in U.S. , considered an Invasive Species.

I'm not in the US, they're legally sold here.

Any insights on the questions I asked?