Veggie or Bog filter?


Joined
Sep 5, 2011
Messages
90
Reaction score
55
Location
ohio
Showcase(s):
1
Hello again!
OK........I have removed my 100 gallon skippy filter and was going to replace it with a bog style filter. Here are the before and after pics.
The new area is 5'x5'x16" deep (approx. 280gal). The area is feed from an submersed pump in the main pond opposite the water falls. The water line is 2" PVC. All the elbows are swooping 90 degrees so to not restrict the water flow. I have cut slots in the bottom of the PVC pipe in the upper filter. The water flow is very good. There is a low spot in this area that I plan to install something like a tower that I can put a sump pump in for cleaning purposes. Also, this empties into a header pond filled with water celery that is approx. 5'x6'x12". Which feeds the main pond.

OK, here is my issue.................I was going to make this a bog style filter. I have enough lava rock to cover the bottom to about 5-6" deep maybe more, topped with pea gravel and of course plants added next spring.
After doing some additional reading and research, I am now thinking of making into a veggie filter. Still putting the lava rock in and then adding the plants next spring.
What I was going for was some filtration that was more natural looking.
Any thoughts either way?
Thanks
Don
 

Attachments

Ad

Advertisements

Joined
Jul 2, 2012
Messages
2,583
Reaction score
1,292
Location
Cape Cod, MA
No real input here, hubby deals with the filtration... just want to say I like the way the new framed area looks. From my UNeducated prospective, I dont think it makes much of a difference which way you go... I think the bigger question is what plants YOU like the look of better?
 
Joined
Sep 5, 2011
Messages
90
Reaction score
55
Location
ohio
Showcase(s):
1
Thanks! As far as plants go, I was thinking something of a tall verigated grass in the back ground, along with some sort of Iris, with a few other types of horsetail, cat tail etc. In front of that, I was thinking water Hyacinth. From what I have read, they multiplye quickly and love to remove nutrients from water. An added bonus is the bloom that they produce. As I have mentioned, I am looking to make this as natural looking as possible.
 
Joined
Jul 2, 2012
Messages
2,583
Reaction score
1,292
Location
Cape Cod, MA
Again, I am not a person who actually deals with filtration but thinking about our bog (incomplete and taken over by comets and shubunkins), my very LIMITED knowledge of veggie filters, and enjoyment of plants... What about splitting the area? Bog style to the back (pvc buried into gravel) with gravel for a planting media for your grasses, iris, horse tail, etc, since you dont usually have to remove these plants... then a veggie area under where you want the seasonal floating plants???
 
Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Because of the size I would call this an up flow gravel filter rather than a bog. These were popular back, 20-25 years. They were just falling out of favor when I first got interested in backyard ponds and was the first filter I ever saw. I only mention this because I think you'd be better off using "up flow gravel filter" as a search term for more research than "bog".

In a bog I don't think it's a good idea to use two different size or shape rock. Water takes the easiest path so it would probably just travel thru the bottom lava rock layer and then almost straight up to the outflow. But in your case the distance from the in to out flow is so short I don't think it matters, and is why I'd call this an up flow gravel filter.

If you wanted this to act more as bog I would bring up the outflow pipe to a little below the gravel surface.

Adding plants bare root would make this a veggie filter imo. And using lava rock vs gravel would be more veggie, larger spaces between rocks. Again because of the small size it could be a veggie. Adding plants, even bare root, to a bog pretty quickly diverts water away from the plants as it's easier for water to flow thru gravel than gravel filled with roots. Bogs are so big compared to flow that water can pick very narrow paths, it's was called channeling in up flow gravel filters. Channeling has never really be discussed with bogs because bog users generally aren't interested in how they work or even how well they work. They just like them. Up flow gravel filters were state of the art in their day and used by people who needed filters that performed well so they tested, dissected, and debated them at length, so a lot more is known about them.

Which way to go depends on your goal. If you want to lower nitrate veggie is better. If you want it to be a settlement tank bog is better. If you want ammonia/nirite conversion up flow gravel is better. However all these filters do all these features to some degree, which may sound good but is also their downside because they don't do any one feature very well long term. Each configuration is just to push their performance in a certain direction.
 
Joined
May 10, 2013
Messages
72
Reaction score
8
Location
NJ zone 5
Waterbug said:
Because of the size I would call this an up flow gravel filter rather than a bog. These were popular back, 20-25 years. They were just falling out of favor when I first got interested in backyard ponds and was the first filter I ever saw. I only mention this because I think you'd be better off using "up flow gravel filter" as a search term for more research than "bog".

In a bog I don't think it's a good idea to use two different size or shape rock. Water takes the easiest path so it would probably just travel thru the bottom lava rock layer and then almost straight up to the outflow. But in your case the distance from the in to out flow is so short I don't think it matters, and is why I'd call this an up flow gravel filter.

If you wanted this to act more as bog I would bring up the outflow pipe to a little below the gravel surface.

Adding plants bare root would make this a veggie filter imo. And using lava rock vs gravel would be more veggie, larger spaces between rocks. Again because of the small size it could be a veggie. Adding plants, even bare root, to a bog pretty quickly diverts water away from the plants as it's easier for water to flow thru gravel than gravel filled with roots. Bogs are so big compared to flow that water can pick very narrow paths, it's was called channeling in up flow gravel filters. Channeling has never really be discussed with bogs because bog users generally aren't interested in how they work or even how well they work. They just like them. Up flow gravel filters were state of the art in their day and used by people who needed filters that performed well so they tested, dissected, and debated them at length, so a lot more is known about them.

Which way to go depends on your goal. If you want to lower nitrate veggie is better. If you want it to be a settlement tank bog is better. If you want ammonia/nirite conversion up flow gravel is better. However all these filters do all these features to some degree, which may sound good but is also their downside because they don't do any one feature very well long term. Each configuration is just to push their performance in a certain direction.
Hi Waterbug,

I know this thread is from a year ago, but I'm in the midst of considering a bog filter or settlement chamber for a small 1800 gallon pond. I'm wondering why one could not just combine the concepts and create a "bog / settlement chamber". This would consist of all the typical features of a bog on the top, but the plantings and gravel would be seperated from the settlement chamber below by a grate and screening. I'm imagining the water entering from low in the settlement area and bubbling up about 18 inches before hitting the bog.

What do you think of this idea? I'd love your thoughts and expertise....
 
Ad

Advertisements

Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Like I said in the quoted text,,,"If you want it to be a settlement tank bog is better".

A bog, as defined in this forum, is primarily a settlement tank. A big round or rectangular structure filled with gravel. Water enters one end and makes its way thru the gravel and exits the opposite end.

The water volume can't all take the shortest path to the outflow because it's no longer the path of least resistance as the spaces between gravel pebbles are too small for all the water volume. So the water is forced to spread out. Spreading out water flow has the effect of slowing water flow. Slower water = settlement. The process is called particle aggregation.

I know many people in this forum despise science, laws of physics, etc, and instead prefer to use their imagination to create a world they like better. But if you're serious about making a functional filter I think it's best to stick with the laws of physics. Leave the pretending to people who build filters as an affectation.

For example, some people choose to add distribution pipes at the bottom of bogs thinking they are somehow "improving" the filter. But it decreases filter performance to a large degree. Water goes fast down the pipe, past most of the filter, and exits the pipe as close to the outflow as possible, and then a fairly short path up thru the gravel so less chance of settlement (particle aggregation) . It's also less chance for any bio filtering, although bogs are already such poor bio filters that the loss isn't much to worry about. Losing 80% of almost nothing is still almost nothing.

Adding an open space beneath the gravel can be as bad or worst than the distribution pipe deal. If the open space were the proper size for a settlement tank (and this can be calculated) then sure, the open space would work as a settlement chamber. The gravel above would have very little effect. The settlement chamber would work basically the same whether the gravel was there or not. However, the cost of the grate would be enormous given the size settlement tanks have to be (bigger than your pond).

If the opening is undersized you'd have the exact same issues as any undersized tank. More water movement than you had in the pond and particles are less likely to fall out of suspension.

Settlement tanks in serious ponds are normally are filled with brushes. The idea is to get the water to spread out, slow down, but also create lots of little eddies which create faster and slower currents, like in a meandering stream which "inner part of the river has less energy and deposits what it is carrying". This allows the settlement tank to be smaller than the pond and still settle out some particles. Just a plain big tank, without brushes, the tank has to be larger than the pond. Otherwise water in the pond will be moving slower than the tank and the pond would be the more effective settlement tank.

Most vortex filters used the same basic idea, but were even less effective than brushes.

Settlement will happen in any size tank, even in a 55 gal drum there will be some settlement. I've read many posts of people with tiny tanks they call settlement tanks and say "works great because when I drain it dirt comes out". Any thing can be called a settlement tank. What I'm talking about is efficiency. I'm on a diet where I eat one less jellybean per year. Yes, that is a "diet", but not too effective. I'd say I was kidding myself. Creating a fantasy world I wanted to live in.

Settlement tanks were once state of the art, but much better methods were found so you don't see settlement tanks being added very often these days to new, serious, ponds.

The reason brushes are used is because they're easy to remove and clean. In serious ponds I've seen online (mostly far east) the entire tank is dumped and hosed down every few days.

Brushes are expensive, gravel is cheap. Gravel serves the same function as the brushes,but even better imo. The downside is it isn't as easy to remove. Not being able to clean a bog is not an issue for low fish load water gardens where water quality isn't a big issue. And bogs work as a darn good settlement tank for 2,3,5, maybe even 10 years. Just like any settlement tank short term crap accumulates and so you don't see it in the pond water, so water is more clear. But as that crap decomposes it will eventually become such small particles (DOCs) that it will no longer stay in the bog or settlement tank. Now I know some bog owners claim to not have any DOCs, but that is 100% pure fantasy and a complete lack of understanding of the must basic pond functions

However, DOCs can be dealt with other ways, like water changes and foam fractionation. But then you kind of have to ask yourself, if I'm having to do water changes to remove waste why not just do that from day one? And why do I need to add a second filter to clean up the mess produced by the bog? That's why bogs aren't used on serious ponds. When I say "serious pond" I mean several things, expensive to build, expensive fish, higher fish load, owners really into the hobby and expect to have the pond for the rest of their lives. I don't know another term to say that. Maybe "more serious" would be better?

While bog's aren't the best filters on the planet I think they'd perfect filters for many, many ponds. Most pond owners are never going to clean filters no matter how easy it is. Even emptying skimmer baskets can be a chore for many people. That's the biggest advantage to a bog, set it and forget it. You can get several years of trouble free use. And for most of these types of ponds they're gong to be filled in before too long anyways for other reasons. Every pond has different needs, every owner different goals. Even if a person wants to believe distribution pipes are great I say that's reason enough to add them. If it makes you happy, do it, if the purpose of the pond is to fill that desire. If the desire is instead having good water quality etc, then filters have to be looked at in a more serious manner to achieve that goal.

Bead filter
An open space beneath the gravel would basically be a bead filter. It's a tank and the beads float. So water has to find it's way thru the beads, slows down, drops waste. But the waste doesn't then fall back down thru the beads into the void below. It stays in the beads. The gravel would work the same way.

In the bead filter the void below is not a settlement area. They just need the extra space during the cleaning cycle where the beads are mixed and "washed" off and the dirty water drained away.

Bead filters where once state of the art and were considered to be the Holy Grail of filters in that they could do both bio and mechanical in one process. But that turned out not to be true. Like all combo filters before it and since, it did neither very well.

With gravel instead of beads cleaning wouldn't be reasonable.

Bottom line
I don't see any upside to creating a void below the gravel. And it would be extremely expensive.
 
Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Here's a diagram of a bead filter.



In your case, with gravel, you would only have "Filtration Mode" top left.
 

HTH

Howard
Joined
Jun 10, 2011
Messages
1,571
Reaction score
783
Location
Oklahoma Panhandle USA
Waterbug

http://serc.carleton.edu/microbelife/research_methods/biogeochemical/organic_carbon.html
DOC is an important component in an ecosystem. It provides a primary food source for aquatic food webs, suggesting that high DOC is beneficial to an ecosystem. However, DOC can also contribute to the acidity of a water body...
It might be that a bog provides a place for that part of an aquatic ecosystem, thinking mostly bacteria, that processes DOCs. I do not know this is true but it seem that it is a likely possibly.

My upflow barrell filter with 1/2 PVC bits does a good job at removing solids and is easily back flushed. The PVC works better after it has been in action for a while. I am guessing that it gets a bit of growth on it and more easily snags particles passing by. Enhansed particle aggregation :)
 
Joined
May 10, 2013
Messages
72
Reaction score
8
Location
NJ zone 5
Thank you for your extensive explanation. I'm sure learning a lot about filtration. Sounds like I'm a bog filter candidate.

In all honesty, I went out to measure my pond site, and it's really looking more like 1000 gallons. I'm thinking of really creating a nice, natural looking pond with goldfish (no koi), plants, a skimmer, and a bog filter and my waterfall.
 
Joined
May 10, 2013
Messages
72
Reaction score
8
Location
NJ zone 5
Waterbug,

I understand your point with not leaving space beneath the gravel, but how about flushing the system to extend the life of the bog? Could one put a bottom drain in and clean out pipe for flushing?
 
Ad

Advertisements

Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
A bog can't be flushed because the muck is in between the pebbles. To release the muck the pebbles have to be moved.

Many filters have the same issue. Bead filters I talked about, the beads are fluidized to wash the muck out from between the beads. Sand and gravel filters air is pumped up thru the sand & gravel to fluidized. Fluidize means to make the media move like a fluid, like clothes in a washing machine. Pad filters, same thing. Muck gets stuck in the small openings and it takes a lot of movement to get the muck to come out. Which is why the mass market pressurized pond filters which can be "back washed" are worthless. Dirt comes out, but most stays in the pads. It seems like it's being cleaned vs actually being cleaned. For that market appearance is more important than function.

You can certainly put in a bottom drain, or several, and when opened pretty gross looking and smelling water can come out. You can look at that and think "wow, I'm cleaning my bog" but that would be kind of a fantasy world. If you then picked any spot in the bog, even above a drain, and dug down what you would find you would probably not call clean. The amount of a muck coming out of the drain is insignificant.

When you buy the gravel you'll probably try and rinse it off before putting it into the pond. You will see the issue right away. Make a small pile, maybe 12" high, 2'x2' and hose it down. Muddy water will flow out and clear pretty quick. Wow, that was easy. Now mix up the pile a little. Hose it down...more muddy water. Repeat as much as you like...but I quit pretty quick. Simply running water over gravel will not clean it.

To fluidize an entire bog you'd have to be talking about maybe $10-50K worth of pumps and a new electrical panel. Not really worth it imo.

People, myself include, get kind of focused on the lifespan of bogs and how it can be extended. That's wasted effort imo. You're losing the most important aspects of a bog...simple, cheap, trouble free. If you're staying awake worrying about a bog design or how it can be improved that's easy,,,don't build a bog. Build a better filter which has already been invented and proven. There are several choices.

Trying to improve a bog is like trying to improve a horse to be more like a car. You can add cup holders, fan, radio, but why not just use a car? A horse is great for what it does, enjoy it.

I'm not saying you shouldn't try to improve a bog, that's everyone's right. Just saying to step back and look at the bigger picture to make sure you really want to go down that path. Plus, every "improvement" I've ever seen made to bogs made it worst not better. Appearance over function. Improving function takes a lot of trial and error. Building, testing and re-building. It's a long and exhausting process that ends in failure most times. This business of imagining improvements is fantasy land stuff. Internet is full of it.

I like bogs primarily as a bed for planting. I just like plants. I like the plants out of the water and you get no string algae in and around the plants. And back when I first installed bogs 15 years ago or so they were decent filters. I don't think I would consider a bog today except for plants. There are just better filters that are cheaper, smaller and no maintenance. For keeping water clear bogs may, and that's only a "may", help keep water a little clearer. They're a long way from being any kind of a solution. I still had to vacuum weekly and run other filters sometimes.

In my future pond I will completely isolate the bog from the pond, so I only add water to replace loss. I've kept several of these in my yard for maybe the past 20 years, even without a pond. They're great. But I would no longer allow water to return to the pond. I want the plants, but also better water quality in the pond. But that's me.
 
Joined
Oct 14, 2011
Messages
1,276
Reaction score
661
Location
Cedar Bluffs, Nebraska
I would like to chime in here to add a bit of my perspective regarding "bogs" as filters.

Waterbug has added so very much to this discussion and I have to say that I am in total agreement with his style and perspective. However, I would like to explain it a little differently and from my own perspective to provide a slightly different angle on the subject of bogs as filters.

First of all, a bog filter is nearly something that occurs naturally, in the wild. Most pond people who adopt the practice are just trying to emulate what nature has to offer. It's a very keen concept and it does work quite well. A mixture of sand and gravel and some water loving plants and some natural chemicals, elements and bacteria and algae all living so symbiotically together to clean whatever water flows through their domain. A bog is a sediment depository, a mechanical filter, a biological filter and a chemical filter all in one. And it usually looks very nice when done properly.

However, the problem with creating a bog synthetically is that it misses the one point in nature that makes a real bog work so well. That is a thing called rejuvenation.

In nature, we refer to this rejuvenation as a major flood, an ice jam, a redirecting of the stream or river channel, etc. Not many pond owners would really desire to subject their setup to such devastations. But, it occurs in nature and it is what destroys one bog to purge it and it creates another.

The larger you build your "synthetic bog" the longer it will last you, but eventually, you're going to have to purge it just like nature does or it will cease to work and cease to exist and it will just become a big muck dump and start belching out the very things that you were trying to avoid. Of course, depending upon the size of the bog, this make take many years as Waterbug indicated, but then again, how much of a mess will it be at the end of 4, 6, 8 or 10 years? I won't ask Waterbug to agree with me on my opinions here, but I personally believe that I am correct to an extent.

I try to think about how nature processes and reporcesses things and why everything we see in nature appears so intriguing and inviting and enjoyable to us. It is because we don't like to look at her when she is destroying one thing and we fail to look at her when she is creating anew. It is only the glory of the finally established gorgeous "end product" that we admire. This is where we miss the point on so many things in nature.

That all being said, I would love the "look" of a bog and the benefits of a bog. I think I would even be happy with the few years of enjoyment from a bog. However, when it finally hung up, I don't know if I would appreciate the cleanup of a bog to renew it. It has to happen "someday", nature shows us this. But it is going to be a foul smelling, tacky, gunky mess! And the larger the bog build, the larger the mess. Mother Nature picks a time to clean up! A bog owner will someday have to as well.

Gordy
 
Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Gordy,

Are we talking about the same thing? You mention a bunch of different things, including "synthetic bog" which I assume is the thing this thread is discussing?

Yes, bogs occur in nature. Yes, we call a lined pit full of pea gravel a bog. But because we choose to steal the word "bog" doesn't mean they're the same thing. In most forums I've been in the term "true bog" must be used when referring to real definition. So unfortunately to use the term "bog", "true bog" or "synthetic bog" you really kind of have to define what it is you're talking about because the term has lost all meaning.

The thing being discussed in this thread so far has be a large round or rectangular lined pit, like 24" deep, filled with pea gravel.

Some people place distribution pipes on the bottom but in the past that wouldn't be a bog. That would would have been called an upflow gravel filter.

What terms people will choose to use tomorrow...who knows. Sure makes discussion difficult.

I don't know of any thing remotely similar in nature. I'm sure there must be something close, but I don't know of it. Maybe a link would help?

No bog I know of, whether in nature or not. contains sand and gravel. A link would help. There are sand & gravel filters, but these have not been called bogs in the past and I hope people aren't going to start now. Confusing enough already. There's formations in the soil that clean water, but these couldn't be considered a bog.

I Googled "bog rejuvenation" and didn't find anything related in the first page. So I don't know what's being referred to. I don't know of anything in nature bog like that is "cleaned' by nature. Things like major flood, an ice jam, a redirecting of the stream or river channel, etc would be very localized and extremely unique events compared to the total amount of normal type "bogs". I would not say the purging of a bog is part of it's normal development cycle unless we use a time scale of millions of years. If we use a time scale of billions of years the entire planet will be cleansed in a super nova. So I think to know what you're referring to deserves a link. But in any case I don't see the connection to backyard ponds.

Catfishnut said:
The larger you build your "synthetic bog" the longer it will last you, but eventually, you're going to have to purge it just like nature does or it will cease to work and cease to exist and it will just become a big muck dump and start belching out the very things that you were trying to avoid. Of course, depending upon the size of the bog, this make take many years as Waterbug indicated, but then again, how much of a mess will it be at the end of 4, 6, 8 or 10 years? I won't ask Waterbug to agree with me on my opinions here, but I personally believe that I am correct to an extent.
I agree. The bigger the bog the longer it lasts. That's really the bog's biggest selling point, set it and forget it.

And yes, I have no way of knowing how long a bog will last for a specific pond, and certainly no way in general. I also can't predict when a specific owner will throw in the towel. When DOC levels get high enough to cause foam on the water surface? Could be 3-5 years. Or so clogged that water starts flowing over the surface? 10-50 years. Or never.

However I do know that a bog will become a "big muck dump" on day one and continue to fill with muck until completely filled. IMO a completely clogged bog is even a better filter because it becomes a stream.

My last point is the Mother Nature thing. There's this thing people do of trying to look at stuff as being natural and that if something can somehow be seen as natural, or even remotely related to nature, it suddenly becomes something good. I think it's a stretch to consider a backyard pond as natural unless it's kept as a wildlife pond. I think we try to create something we see as natural. It's a fantasy. Like how most people no longer know what a gunshot sounds like because we now consider movie sound effects as the real thing. We've been conditioned to see clear water filled with super colorful fish with a waterfall that materializes out of no where as the new standard for natural. I think it's fine to see a pond as natural. But it gets really confusing when that fantasy is applied to real problems like filtering water.
 
Joined
May 10, 2013
Messages
72
Reaction score
8
Location
NJ zone 5
Water bug,

Thanks for the explanation. Looks like my pond has been downsized to 1000 gallons. Still want fish. What size settlement chamber would be minimum for that size? And is there any advantage to more vertical space over horizontal in a settlement chamber design?
 
Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Oh there's no data at all on bogs, size vs performance. I've never heard of anyone ever testing any kind of parameters related to a bog. It's a kind of filter that's used by people who don't test and measure stuff.

So generally what people do, to sound like experts, is to say something like a bog should be X% of the pond. Or "mine is X big and I have perfect water because it looks good to me".

Testing and measuring filter performance is only done by people who really need a filter to do something. Most ponds go clear without a bog. But every pond that goes clear AND has a bog the bog gets full credit. If the pond isn't clear the bog is said to not be big enough, even though "big enough" is never actually defined.

There is no advantage to vertical vs horizontal space as far as anyone has shown. As for theories I can come up with several for both cases.

My advice...build it as big as you'd like it to be.

If you can have the bog outflow go into even a short stream before going into the pond that would be a plus. You have to expect the water coming out to be low O2 and high bad gases, so some gas exchange before the pond would be nice. In a pond with a few small fish this is generally no big deal. But higher O2 is considered a plus.

Plus even a short shallow stream is a proven good bio filter and gas exchange and possible could grow macroalgae which may kill green water algae. Some of the best bio filters are based on streams.
 
  • Like
Reactions: HTH
Ad

Advertisements

Joined
May 10, 2013
Messages
72
Reaction score
8
Location
NJ zone 5
Thanks Waterbug. I should have been clearer in my post. sorry.

I'm thinking of more traditional filtration now for my pond. I'm thinking of of a diy system similar to this -
http://www.earthangroup.com.au/diy-b...l-flow-filter/

But, I would use two 30 gallon drums in-line (one for for mechanical / one for biological). Both below pond level and gravity fed. This would clean a 1000 gallon goldfish pond. I'm wondering if 30 gallons good enough? I'm thinking this will provide more filtration than a bog, easier to clean, etc. But, I've seen most use 55 gallon drums.
 
Joined
Apr 10, 2010
Messages
3,219
Reaction score
1,295
Location
Phoenix AZ
Oh I see now. By "bog" you mean a filter that has absolutely nothing to do with a bog and in way whatsoever.

Yeah, the 30 gal will be perfect.
 

HARO

Pondcrastinator
Joined
Jun 30, 2011
Messages
4,939
Reaction score
5,243
Location
Ontario, Canada
Hardiness Zone
5b
Country
Canada
I live about 3/4 of a mile from a bog. Not a gravel pit with an upflow of water, but a REAL bog! Lord knows how long it's been in existance, but I'm sure it's been several thousand years. Currently it is about ten acres in size, and the sphagnum moss it contains feels like it's about 20' deep when you walk over it. Rubber boots are a good idea, for although it contains no visible water, your feet WILL get wet. The surface of this bog is covered with cattails, sedges, various reeds, cotton grass, pink ladies' slippers and many other plants. Scrubby willows form a taller ring of vegetation around it, while cedars are starting to close in around the perimeter. Does anyone really believe that this can be replicated in a corner of a suburban back yard? Let's call these structures what they are... gravel filters, vegetative filters, or whatever, but they are NOT bogs, any more than a backyard pond is an ocean!
John
 
Ad

Advertisements

Joined
Oct 14, 2011
Messages
1,276
Reaction score
661
Location
Cedar Bluffs, Nebraska
Waterbug,

To clarify some of my points regarding bogs:

I can cite no reference where I gathered the notion of a bog except for "nature" itself and according to the real definition you linked to, what I have seen in nature is NOT a true bog. Locally here, along and within the Platte River of Nebraska and in the sandhills of Nebraska there are large expanses of wetlands or "marshes". The soil composition is primarily sand and gravel with vegetation growing in very wet conditions. The "wet" could be anything from a slow trickle flow through the sand and gravel to even small rivulettees meandering between the vegetation with lots of springs and pools and the water disappears underground for a distance and then reemerges as a spring. At the outlet of the "bog" (or should I call it a "marsh"?), the water comes out pure and clear. This was my definition of a natural bog, and it seemed to reflect the very aspect of what everyone was doing or creating as a "bog filter" for their ponds.

Rejuvenation of these marshes in nature came from the change of seasons mostly. Winter freezes and floods would scour them out and replace them with new material or at least turn the old over and stir it up. The landscape of the marsh would become totally changed, but it would still be there. On the river (Platte River) such marshes would typically be found on some of the islands scattered all throughout the river valley. These would come and go over time. Major ice-jam floods would either erase them or create new ones. High water levels would tend to purge them like backflushing a slow-sand filter. If the water doesn't get high or flood enough or if there aren't any ice-jam floods and maybe there is a drought, the marsh slowly closes up. The short vegetation gives way to trees and vines and eventually the marsh is gone completely. But, several years down the road, nature reclaims her rite and scours out a new streambed that will eventually become a boggy marsh.

I have witnessed these "marshes" all my life and I was fascinated by them. When I started reading about "bog" filters here and read some of the descriptions, I branded that concept with my past experiences in nature from my local environment. I studied these systems (not scientifically, just observing and learning and enjoying) and I see that they really work very well! I therefore believe that these "bog" filter systems are highly beneficial and effective for pond owners, but I stress the importance of the "size" of the bog, the materials used and the design.

The term "synthetic" to me just means to emulate what you interpret from nature. You cannot truly duplicate it, but you can give it a fair shot, but it will not be a BOG. I guess that is just a quaint term that is easy to use and remember, but you are correct, it is a misnomer.

Gordy
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Top