To save on costs for heating, during the day when you are not home you could keep it covered with a solar cover and throughout the night to keep the heat in. When you want to enjoy the fish on the weekends when you are off, you can unroll the solar cover and plug the heating system in. As far as filtration is concerned, I think a couple of high output sand filters would do the trick and you could vaccum the bottom the same way you would a normal pool. I don't see why it couldn't work, especially with the warmer average temperatures in So cal. I've personally thought about it as well but it wouldn't be feasible for me with the winter climate in new York. I hope you do it so I can experience it vicariously through you lol.