In addition to the fish pond, there is a cascade. Water in the large (50 gallon) pool at the bottom is pumped to the top pan (5 gallon) and cascades down the 3 cascade pan to the bottom. The pump for this set is about 150 G/H and sucks in a lot of stuff. After replacing the pump because of jams a couple of times, I came up with a filter system that seems to work. I used a plastic basket that you may be able to find in the same area of the store where the pumps are sold. The baskets were originally intended to hold the roots of water-plants together when they must be removed to clean the pond. I used the a square piece of plastic (cut from the bottom of a cat litter pan) to make a bottom. The bottom is loosely retained with a couple of rings made with wire, twisted to close them. The hose of the pump is punched through a hole cut in the bottom (now the top) of the basket. The trash filter on the pump acts as the final defense but the plant-basket filter provides a large area screen that is fairly fine. The only problem I have had is if it goes more than a week, the suction on the clogged basket filter flattens the basket. Regular maintenance is essential.
I usually just leave this pump running when cleaning. Lift the pump and filter out of the pond. Detach the hose from the pump to free the basket-filter. Use a hose or brush to clean the filter. Use a hose or brush to clean the trash filter on the pump. Put the hose back through the hole in the basket and insert the pump outlet in the hose. Close the white lid, lower into the water and check the flow. Put the brick back on the basket-filter to keep the lid closed.