I collect any kind of pieces of plastic for media -- bottle caps, drinking straws, leftover pieces of pvc pipe, I put them in a mesh bag and toss in a filter. It's probably all thrown away now, but Easter basket "grass" stuffed in a nylon stocking is very nice. I've heard of cutting 5/8" drip irrigation hose into pieces 1 1/2 inches long. It's a very nice product (and cheap) but that's a lot of cutting.

Biofil. Is the Best thing I have found. One of the most important things is a Uv light

Another thing people have mentioned is the plastic deer fencing. I make scrubbies out of nylon net from the fabric store and when I got tired of making them I just scrunched up the net and it works just fine. It's not expensive. I also use washable air conditioner filter material. It lasts and lasts.

Plastic pot scrubbers from the dollar store. Cheap and they work very well.

Plastic pot scrubbers is what I bought last year and I have several of them in there, I will look at buying some more. Regarding the deer fencing, that's what my prior pond had as it's filter medium. It didn't work the best but I believe that's because I did not clean it often enough and the pump I had was a bit underpowered. Thanks for all of the ideas guys!