I have a decent sized pond currently, around 20 feet long by 10 feet wide and 6 feet deep. I just used a 55 gallon trash can and STUFFED it with filter material and its working great. Its powered by a 3200gph pump and a 1200 gallon pump and has 3 inch outlet and two 1.75 outlets next to it with a soda holder to disperse the water as a bakki shower filter. I also used a shopping basket to right above the outlet at the bottom so it wont get clogged. Its just enough to keep the water clean and in good condition. I also have a uv light attached to the 1200gph pump.
Heres a picture. PS dont buy that bs filter media at the local pond stores. Go to homedepot or lowes and get some swamp cooler media. (its blue padding) it works 100 times better and it will be much easier to clean as large/small objects wont get suck in it. 30 bucks at lowes will be about 200 bucks of filter media at the local pond supply store. As my local pond store sells a foot for 7 bucks!!!!