Comment: You would need a ten story structure over your pool

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In reply to comment: or the swimming pools! (see in situ)

You would need a ten story structure over your pool

to handle all of the grow space required to maintain a reservoir like that.

You see aquaponics requires a balance between growspace:water:fish or it won't work correctly

A more practical thing to do would be to have a small pond in the deep end only, use the pool's plumbing for moving water, and the green house in the rest of the unoccupied pool space.

I am really considering starting a business up here in Toronto refurbishing old pools, that cost too much to maintain, into gardens like i have described above.