This was suggested by Mikeselectricstuff. It's a floating fountain that pumps water at surprisingly low light levels.
https://www.youtube.com/watch?v=y9BvhPG-rQE
I didn't get into it as far as I wanted to, because the two main electronic modules are potted in black resin to protect them from water ingress.
Gordo
2019-07-17 21:11:01 +0000 UTCBig Clive
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