1 bucket (minimum 5-gallon, but you can go bigger if you want)
About 4 feet of 1/2" PVC (again, for large ponds/pumps, go with 3/4 or 1" pipe)
2 PVC elbows non-threaded
1 PVC elbow female threaded on one end
1 PVC Tee non-threaded
1 connector male thread/hose bib to match your hose
teflon tape for taping threads
1 PVC straight connector (for outlet tube)
length of hose (I used old garden hose 5/8"id)
1 hose clamp
Stiff screen or mesh (I used 1/2" mesh)
Thin window screen (optional, depending on media used)
Bio-filter balls, lava rock, or both (I had and used both)
Silicone or gutter caulk for outlet hole
Take a 5 gallon bucket, some 1/2 inch PVC and fittings and assembled as you see below.
Cut a hole in the side about 4" from the top and inserted the outlet tube. The straight connector (under the screen cover in the pic) helps form the seal.
Using gutter caulk or silicone, seal the outlet tube well.
The idea is to make the water cyclone in the bottom. It keeps the inlet clean as it pushes the water up through the filter. Use a mesh that is strong enough to hold your filtering media up off the bottom of the bucket.
I added a few bio bags from the fish store. I don't know if they help, but I'm sure they can't hurt. One of them I pulled directly out of my fish tank in my house. The thought is that some of the beneficial bacteria that keeps the little fish tank clean will help the pond.
Fill with bio-media.
Attach hose and clamp. Turn it on and check for leaks. I don't care as much about how it looks as I do about safety and water retention, so I just hang the edge of the filter over the edge of the pond. That way if the outlet tube ever leaks it will just drip back into the pond.
Notice this filter has no lid and is not pressurized. It does not need to be. The filter has never clogged or overflowed. It has worked flawlessly.
The only negative about this filter is that it's an eyesore!
I thought that if I wanted to improve the look I could put a decorative barrel over the entire filter, but that's for another day!
Feel free to comment with questions or design ideas...