Our friends Greg & Linda at the neighboring horse farm Hacienda Siesta Alegre gave us these used carpets to help pad the ground when we put in the pond liner. They bring the carpets in from Florida to use as padding on the floor of the airplanes which they ship thoroughbred race horses in to local horse farms and for the race track here in Puerto Rico. So these carpets will have been recycled twice.
It took me a while to figure out how to plumb this. The majority of the water is going to pump directly to the waterfall but some of it has to go through the bio-filter (not too much as you don't want to upset the balance of organisms living there which do your filtration). So there are two gate valves to regulate those flows. Then there is an over-flow basin for when the pond gets to high and a big ball valve to open the pump directly to the overflow for when you want to drain the pond. Then another basin drain in the bio-filter tank so you can clean it out.