I have a DIY filter that I designed and built that uses air. I am using 2 of these filters now and LOVE them. they are inexpensive to build (although the filter media I have selected is not cheap) and they are a snap to clean. On the down side...the first part of the system (the mechanical filtration) does clog with plant fibers so if you have a watergarden this may not be the idea filter for you. An air pump aerates the second part of the filter all the time...this is my bio-filtration. When I want to clean the mechaical filtration, I simply turn two valves and divert all the air to an air ring that is in the bottom of the static K1 filter. This boils the media clean in a few minutes. Here is a link that might be useful: diy filter

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.

Disclaimer: I'm the last one here to be offering advice, lol. HOWEVER, I can share my experience which is a result of all the wonderful advice I've received here over the years. I have a small pond...actually three pre-forms joined together. I built my skippy using a large lotus pot (the better to disguise it with, my dear). I have plastic lighting grate over the pvc pipe in the bottom. Then a SINGLE piece of a/c filter, then scrubbies topped with quilt batting and another piece of light grating on top. I sprig my plants into that. Ends up looking like a large mixed container with lots of texture and *voila* the skippy is invisible. I will add that, since I built the skippy 3 yrs ago, I've had gin clear water ever since. Ha. Reading back over your question, I could have just said 'leave it flat' and skipped over the details. Oh well. Hope this helps. ~digger

It is the strong root structure that you want in there, to eat up the nutrients. The more roots the better does the job. That is why Watercress and the other plants suggested, do so good a job, they have a gazillion roots. hawkiefriend. As to your filter lid if it is a vacuum filter the lid should surely be kept on, as "pikecoe" mentioned!? "Horton"