im thinking of doing an outdoor pond in awhile with koi (would do tropical fish but i've heard it wont work with the phx az winters of 45degrees wind chill at night, plus i really dont want to do heaters for a 1000 gallon+ pond) anyways, my dad has an old pool pump that he isnt going to use, so could i use the pool pump and buy a 1000 gal+ pond filter? would this work or not?