Mock up time. As mentioned I want a pool area lol - maybe waterfall ... anyway ... mocked the basin up (40x50x15cm or 15.7x19.6x6")
That's 30 litres or 6.6 UK / 8 UK gallons
It will have a drain and pump with filter - assuming I go with waterfall - not 100% yet ... I got all the material but need to mock that also up to decide.
PS: That isn't the substrate for the snake - that's background soil as I am using the viv to build those.