Oldhead,
Is that "sludge" build up or is it bacteria colonies?
What exactly is it that you are using that you refer to as deer fence? Is it vinyl coated wire or purely vinyl fencing like the new style snow-fencing?
I always remember the old wire-wrapped wood lattice snow fences from days of yore, but they make all sorts of totally plastic based snow fences nowadays. Especially the orange colored stuff and even the black colored stuff that I often see used along the highways and interstates in the medians and ditches to break the rain water runoff and deter erosion.
I believe that just about anything will work, but I can see several options being much better than others. I personally don't like the idea of anything with a lot of "flat" surface area. Like the green strapping material shown in part of the video that you posted. I know this stuff as we have it at work for strapping bundles of fiber. I think that it is too slick (finish wise) and unless you wrap it up into coils in a specific way, you can easily negate the advantages of what surface area is available as the straps can lay over top of one another and basically close off much of the surface area space for bacterial use. I think the notion of bathroom or toilet brushes would be much more effective that the strapping material, but I don't see the brushes themselves being all that great either. I think the brush bristle structure is great, but combined with the head and the handles of the brush, I think that there is a lot of volume that is wasted.
I chose the Kaldnes K3 media personally. I know that it is expensive, but the geometric structure of the discs seems just right for the job to me. It's meant to be used as a "moving bed" filter media, but judging from the structure, I don't see why it couldn't serve just as well if it were packed into a confined vessel and the water just run through it.
My concept may not be accurate, but I have a gut instinct that there are two major qualities that are desired. High water flow with little or no restriction and a very large surface area for the water to come in contact with. Besides that, it should be OPEN enough that the bacteria culture growth will not close up the pores or channels and it should NOT allow algae growth within it.
I guess I don't like flat surfaces much. It just seems to me that such structures can stick to eachother or lay against eachother and close off pathways too readily. Pathways for water should be wide open as to not restrict the flow, but still be able to pass over each bacterial culture so that the bacteria can come into contact with the water and "scrub" the ammonia or nitrites and other chemicals out of it.
If you want to do this within a confined space, you must get the "mesh" of the biological filter just right for your specific application.
Such a biological filter (converter) can be fabricated to be extremely efficient if thought out very methodically.
I don't believe that I am thinking too hard on this issue, it just seems logical to me that a person designing a filtration and a bio-converter should strive for the best possible design at the least possible cost. If some sort of media is free for the taking, I see no problem in utilizing it if it may work acceptably. But, I wouldn't go out and purchase anything that has not been proven to work.
Well, anyway these are just my humble thoughts about media for a bio-converter. I will let it go at that and allow you to pick your media through your own accord.
I wish you good luck with whatever you test, but don't forget to report back with the results here (pro or con).
Gordy
