Backyards vary considerably in size and shape, so I can only offer general guidelines for your pond setup. The pond should be proportional to the yard. This is a design consideration that is defined by the yard’s dimensions and overall size. Many homes have smaller yards, and in some cases, they may not have space for an in-ground pond. Above-ground ponds are possible using a variety of materials to make the exterior of a liner pond look attractive, but such ponds are so small that exposure to the elements results in considerable heating in summer from sunlight and freezing in winter, except where winters are mild.
The shape of the pond should be given some thought. A round pond is basically unattractive and unnatural in appearance. On the other hand, an intricate outline, while perhaps more natural, can interfere with good water-flow patterns within the pond, resulting in stagnant areas where algae can become a problem. Most well-designed ponds have some variation of the classic kidney shape but have some irregularities in the outline that give it visual interest and a more natural look. Some people prefer a formal look, which may be reflected in the rest of the yard. In this case, an outline of straight lines and right-angle corners can be used; however, if you would like wildlife to visit your pond, this will limit access because of the lack of shallow areas along the edge.