Hypothetical question for best land grade in a 1 mile diameter cylinder

From: Xenophile

"I'm rather fond of the idea of having the window areas double as
lakes. "

If you keep the water as filtered as a swimming pool, it'd be clear enough
to do this, and such a pool might be an interesting showpiece for the
habitat. But, if you actually try to make `lakes', with fish, and other
living organisms throughout, I don't believe you'll have enough clarity to
pass sufficient light through.

Dave