This is one of my favourite builds.
There are two ponds connected by waterfall with a feature rock fountain in the top pond. The ponds are fibreglass lined reinforced concrete ponds with all vertical sides. The pond is set up for easy and versatile operation with the waterfall and fountain being switchable and the filtration cleaning process being mess free. The ponds are landscaped into a mature rockery and garden and populated with a great selection of koi.