I always assumed the brown leaves are just dried up greens ?. I'll leave it in the sun tomorrow. The mauritian summer sun should take care of it in a day or two
but... Thailand?
I'd expect it to be all over the place, every condo or hotel's landscaped garden, no?
Current leaves are lasting maybe a fortnight, leaving the veining (stock incl. snails/MTS, RTS, goby & pleco).
Far less tannin/water stain than I remember, maybe a seasonal thing or bad memory.