i want to put something outside and put some fish ( dont know what yet) into it and i was wondering what i could do to help keep it cool... im not sure if im going to even do this, but it sounds like it might be interesting. what could i do for filtration? anyone know how to make a diy pond filter? and what kind of plants would be good to put in it? i dont want it to have a lot of different plants, just something for shelter and to help with nitrates and everything else...