BTW I have something similar you have, though I sort of forgot about it for a while since I am too busy
I have a 40l vase, with hornwort, near the window, and I also have a 3l jar, with substrate.
Both houses pond snails. It doesnt have a heater, and air stone or anything, just water in a jug sort of thing.
I do top water or change water every once a month or so. The hornwort is the best, because by shedding the needles, they decompose, cause bacteria, cause fertilizer to be in the water, the plant is doing ok. Also the shedded leaves are consumed by the snails.
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The anubias one doesnt fare as well, I just checked, lot of empty snail shells, I assume they didnt have enough to eat.
If you go in a way of slower growing plants, you will have to feed a tiny bit at least to keep the snail happy.
BTW both tanks are room temp, which sadly now is 17° and both are doing ok. Interesting, since anubias should not be able to handle below 20°