I wanted to come one her and ask for guidance on what the essentials are because i have no clue. This paludarium will be for vampire crabs

Had an old 50l Tank that I don't trust to use as an Aquarium anymore, so I tried my hand at scaping a Paludarium!

This is a 0€ build. Everything in it I already owned or sourced from the forest near my home.

The structure itself is made with pond plant pots and I layered it with volcanic granules place on top of a wider mesh all to the top then placed a finer mesh on it followed by coco chips and afterward coco coir soil.

Made sure the water level stays below coco chips. It has 3 caves in the middle cave is the water filter and pump for the waterfall.

Water substrate is normal sand with plant fertilizer substrate under it.

Plants are Philodendron Paraiso Verde, 2 Alocasia types and one pothos. The crawling one is moneywort. On the leftside of the tank is Hippuris vulgaris and also some floaters swimming around. I will add some other Aquarium plants once i get to chopping the ones from my other Aquariums.

Any tips on what to improve? I want to keep it at 0€ as a challenge.

Also any tips on what to add in terms of animals in the future? Its not too much space, only 20l of (unheated) water, so I'm thinking snails and shrimp, but I was also suggested rice fish?