I would advise against it. Bogs may have some filtering
ability theirs is much less than other plants. Water enterring most bogs runs across the surface since a bog
is already saturated and has some percolation into the underlying soil mass.
Certain aquatic plants have a much higher effect in natural filtration systems. In fact one, the common weed in florida, water hyacinth has been used in some public water works-i cannot recall offhand but could be goggled?
What I would recommend is building another small pond above the lower pond and planting it with cattails and other marginal plants that grow out into the water and have lots of roots-such as Water Smartweed and also have submerged plants such as milfoil. What I would suggest is presuming your upper pool runs from west to east where the water fall is to plant the low marginals along the eastern edge and into the shallow portion of the eastern edge, then submerged plants and then on the western edge sedges and cattails. This would be like a coarse screen then finer screens.
On the Jack in the Pulpit-leave it where it is happy. It is not really a bog or aquatic type plant. You may want to consider Water Arum and one that I think is called Skunk Cabbage-I could be wrong on this name. Check out the water plant nurseries online.
Cheers.

T-man is right, marginals would be a better filter.... but, don't let that stop you from building a bog somewhere in your system! ;o)

We're actually considering doign a pond this summer and I've also thought about including a bog as part of the system. My idea was running it through a pool of marginals before I let it seep through a bog system. I was thinking that such a system might be one way those of us on the east coast could grow Darligtonia (which requires cool roots).

So, to echo what kwoods said, include a bog as part of the system if you like, but use marginals like cattails to do your filtering. Also, under such a setup you'd need to be careful of how many and what type of fish you have. too many fish would pollute the bog, and the bog might contribute too much acid for the fish.

Anyone out there done this experiment before?

I haven't really done this before-I have created a small
bog in a half-barrel liner. But I have visited a bog and what the bog I visited is like is:
it sits out in the open abutting a conifer forest on two
sides of a wedge-shaped clearing.
the primary but actually it is hard to tell what is primary
as there are many streamlets flowing through it downward to
the wide side of the wedge.
on the wide side of the wedge are marginals then out into a
large pool or pond.
While having an in-ground bog sounds great to me it is not
really possible because of our local water quality-too many dissolved minerals that even with buffering still works
havoc with sensitive plants.
But to build one I would think that it should be like an adjunct or a low area on the side of the main water flow where water backs into it like being deflected by large boulders and is eddyied into an area that is separated but has a just barely floodable lip through which water can seep into the bog.
Either this kind or one where the water flow ends up in a bog and a recirculating pump is installed at a collector pool on the lowest point on the bog. Marginals can be installed at the high end and the larger vasculars can deal with the impact of fish in the pool(s).
Here is a link to an interesting site that might be of value
Bogging in Texas

Very few people have the soil to do an inground bog with native soil. That's the second major function of the liner. It is meant not only to keep water in, but also to keep excess minerals out.

As your link points out, A bog garden cannot recreate a natural bog (which can take hundreds or thousands of years to create). It is merely a human simulation, but educational, beautiful and fun nonetheless.

In my set-up the bog is actually at the top of the "system". I can direct limited flow to it only when it needs it.

I have a small pond that flows down a small waterfall to a second larger pond. The recirculating pump is in the lower pond and flows to the upper pond (classic waterfall setup). However, I have a T valve I can switch so water flows into the bog to flood it or just get it moist. When I switch it to flow to the bog the bog then overflows to the small pond but only a small amount.

I have a few marginals in the upper pond. If I was going to have an area of just marginals I would alter the setup to have that at the top and the bog could be anywhere off to the side.

Here are a couple of links pertaining to bogs.
I was trying to find some cool images of bogs but no luck
with the time I have (got to get to work!)

Brooklyn Botanic Garden

James Deem site

Cheers.

This is actually fairly common practise, its not so much a filter as a filter component, ponds don't really need filters anyways, if you have a bog as part of your pond systtem and pump water through it the orgainic load will be lessened, but you must also keep in mind that your tannon will go through the roof, its a trade off, but it is a natural paring in my eye, just don't overstock/overfeed your pond and you wont destroy the bog portion.

I plan to use my new bog as a filter, this pond new last spring 4 feet deep, 2000 gallons. I have to clean my bio falls filter pads and my bio mechanical filter pads every week, despite great airation and really only six fish. I plan to put a bog to the left here to the fence. see http://dunn.smugmug.com/gallery/498262/6/69707551
my idea is to have it flow back into the pond from the bio filter, with lots of plants in it.

Here is a link that might be useful: pond

Check out information on "biologial pond filters". We pump through a half barrel with volcanic rock in it to filter our 600 gallon pond. It also has a drain for cleaning which only requires turning off the pump and spraying it with clean water. I think you may be disappointed with the bog filter idea. The biggest problem I ever had with my pond was trying to remove the iris from the biological filter. Bog plants can be really invasive and your bog may end up a real mass of roots with all the added nutrients from the pond water.

Based on my research it seems that the term bog is used for fiultering but when used in this case it means something different than a traditional bog. the filter is set up so that the water is pumped up through the bog, not flowing over it. The bog is made up of either fine gravel or sand, and the plants could be either bog plants or marginals.

When set up in this fashion, the bog should work well as a filter??

I built something like what madtripper describes in one of my in pond bogs. When we built the pond we had 2 areas made shallow with some seperation from the rest of the pond (the 2 bogs). I put pea gravel over the outflow which is essentially like a soaker hose only made of pvc. Then I put a layer of fairly inorganic clay over that & planted some stuff. My plan is to harvest the plants as they grow as a way to take nutrients out of the pond. I sort of do that anyway because there is always some algae to be removed.

It looks really cool - kind of like a natural spring welling up from the ground when I have it turned on high enough. I went back and installed a valve after I put it together so that I could control the outflow to the bog, 2 waterfalls, & cattail "filter" (basically the sort of marginal filter that most folks have suggested).

Is it working?? I do have significantly less algae this year but my pond is still maturing so I am not sure it is due to the bog filter (its 3 yrs. old & 2000 gallons). I don't keep a big bioload - just some mosquito fish and some frogs.

I wouldn't say "WOW! it has made a huge difference" & the cattail filter certainly can handle a higher gph. I would recomend the later if you are choosing but the bog filter is very attractive and was fun to build.

My water is clear all year round (not totally algae free but clear). I used to have so much algae that I did daily removals and it covered the surface of the pond if I skipped a day(now I am down to once a week & I can wait 2 if I don't get to it).

ADVICE FOR FOLKS WITH HIGH ALGAE OR CLOUDY WATER
My take on the whole algae/nutrient control things is first 1) keep your stocking level low, 2) make sure you have fair water circulation, 3) make sure you have enough oxygenators to take up extra nutrients, 4) remove leaves when they fall, 5) keep at least 2/3 of the pond surface covered with lily-pads or shaded during the summer and 6) try to use soft water for filling & topping off. If you still are having trouble play with a cattail or other emergent filter.