" Can't it just be anywhere that supports this growth?"

Indeed it can! And it is everywhere on your stream bottom and sides, in your bog garden and on the walls and bottom of your pond.
If your water is clear and all the parameters are in tune, why change anything?

You have a natural filtering system going there with the stream and bog garden. That is top drawer in my opinion.

With any garden pond water filtering material, there is bound to be some "channeling", where some of the water passes through "untreated". But it will eventually pass through the filtering material at some point.
It is not as if you are filtering the water for human consumption and have to micro manage the filtering.

I don't believe that placing pot scrubbers around will do all that much better a job, than you seem to have at the moment, but it certainly will not hurt anything.
Remember you will have to clean them once in a while..
"Horton"

I am somewhat bemused by your questions and expect this will need to be answered by more than one person.
The function of a filtration system is to concentrate filtering capability into the smallest space. Your system would work to a point but would eventually be overwhelmed by particulate matter and bio material will escape one trap after another to feed an algae bloom where in a filter of some sort it would escape one to be trapped by another. It is simply more efficient than your free system. Sandy

I ditto what Horton said. It sounds like everything is working just fine as is! If you want to add a bit more filtration I would just add some floating plants to the those little pooled areas instead of scrubbers. Plants like Water Hyacinth, Water Lettuce or Frogbit will filter your water silently while they sit there and look pretty. And...you don't have to rinse them! LOL!

Nance

Sandy, what you point out, is not without merit.
I figured some one would bring up the fact, that there is no mechanical filtration as such, to trap the particulate and bio-material, as you mentioned.

Certainly at some point the OP, "mawkin", will have to clean out the sludge and other built up material, that is left over from decomposed plants, etc, since it is a closed system he has there. [As most of us with ponds have].

The secret I guess, is not to allow the nasty junk to build up to the point, where it does overwhelm the natural filtration and balance that is there and coping at present.
Your comments are certainly valid.
"Horton"

Sandy, what you point out, is not without merit.
I figured some one would bring up the fact, that there is no mechanical filtration as such, to trap the particulate and bio-material, as you mentioned.

Certainly at some point the OP, "mawkin", will have to clean out the sludge and other built up material, that is left over from decomposed plants, etc, since it is a closed system he has there. [As most of us with ponds have].

The secret I guess, is not to allow the nasty junk to build up to the point, where it does overwhelm the natural filtration and balance that is there and coping at present.
Your comments are certainly valid.
"Horton"

Thank you for the comments. My idea was spurred partly because the skippy filter page makes a big deal about not ever cleaning the filter. It seemed logical to me that, if the goal were to put a system in place that would never be cleaned, it would be more likely to succeed if the bio-material were not, in fact, concentrated in the smallest possible place, but, rather, that the process of biological breakdown were spread over the largest area possible.

In any case, I think the suggestion to just pack in more plants, rather than try to make it into a giant skippy filter, makes the most sense. If it looks like it isn't working, I can always add a filter.

Thanks again.

Mawkin,

How much cleaning you have to do in your pond is dependent on how well your bog is working. If it's working, don't fix it and just count your blessings because not all homemade bogs work that perfectly. Adding floating plants to your stream can only increase the amount of filtering and ease your load of care. If however you want to improve your bog, check the link below. Notice in the posting they say they would have even less maintenance if they had a bottom drain. Is it necessary? Nope.

I do not have a bog filter. I can tell you this though, when we build our new and improved pond it will have a bog filter. And I will tweak it and tweak it till it's juuuust right. LOL!

Google BOG FILTER and you'll find more information as well as great construction instructions like the ones below.

http://www.nelsonwatergardens.com/data/resources/other/1_Bog%20Filter%20Construction.pdf

Nance

Here is a link that might be useful: Bog garden forum

If the gravel is deep eniough it should also work as a mechanical filter. It will help to trap the particles and even larger stuff. Adding a pad would increase the surface area but it also means keeping an eye on the areas around the pad to ensure it does not clog up and cause overflow. Adding in plants will work in the same way as adding the pads the rootball will eventually form a dense pad. Watch around the plants because they can block the water flow, especially agressive growers. I have water mint and watercress in my spillway and I have to go out once a week to cut back the roots and offshoots to keep the water from backing up over the edge. Of course it depends how big the plants is and how big the stream is whether it would get to that point. It should look beautiful once it is all planted. Good luck

If anything, this thread has convinced me to just relax and enjoy.

There ya go! LOL! And just to add to all those good tips... it's worth reminding to not overstock or overfeed the fish. No reason for those plants to work any harder than we would want to! ;-)

Nance