Posted: 30/08/2013 at 02:14
i think the key to healthy outdoor fish is the amount of underwater plants. i've had outdoor ponds, from small 12in diameter pots, to bigger 6ft length ponds. none of them have had any filteration. the fish thrive because i have 70% or more of the container/pond filled with underwater plants and algae.
also u mentioned lily pads. make sure u keep them at bay because they can easily grow to cover the surface which will reduce water/air surface area.