This family converted an unused swimming pool into a greenhouse that grows produce tilapia fish, and chickens for eggs. Pretty ingenious. (There must be some mistake though, why would rainwater go with gray water?)
These folks feed their family with a garden in their swimming pool — and you can, too
Instead of commercial fertilizer, chicken droppings fall through wire mesh strung across the pool’s deep end, nourishing the algae & duckweed in the pond below. The tilapia eat the pond plants, release their own nitrogen-rich excrement, & the fish water then gets funneled (using a solar-powered electric pump) into the hydroponics system that grows the family produce.
Cost of shipping a dimensional object ~5m wide makes this something to make 'on site'. A roll bender, 2" steel pipe and 6" pvc pipe are the main materials. The larger the diameter the higher the yield in the area.