Bog building, also called upflow filter, eco filter, wetland filter

[Lisak1]

@MTguy - waterfall foam is great for diverting water flow. However it is not a product that will create a waterproof seal. Another concern I would have is that it has a lifespan. Our pond is 8 years old and we have already had to re-foam some parts of our waterfall. The foam adheres to rocks, but not forever, if that makes sense. It seems to shrink up over time which allows it to get dislodged. Plus rocks will shift which will also break that seal.

I don't know if I fully understand your thought process, but maybe knowing our experience with waterfall foam will help you decide if ti will work.

 

[MTguy]

@MTguy - waterfall foam is great for diverting water flow. However it is not a product that will create a waterproof seal. Another concern I would have is that it has a lifespan. Our pond is 8 years old and we have already had to re-foam some parts of our waterfall. The foam adheres to rocks, but not forever, if that makes sense. It seems to shrink up over time which allows it to get dislodged. Plus rocks will shift which will also break that seal.

I don't know if I fully understand your thought process, but maybe knowing our experience with waterfall foam will help you decide if ti will work.

That was very helpful, and I appreciate it. I kind of assumed it would degrade but wasn’t sure if smaller rock would “lock” into place with the foam and then when the foam degrades the rocks would still be there. Either way, looks like I’m back to the drawing board!

Thanks for the feedback everyone. I would like to get as much right on the first attempt as possible. Sometimes I go down some pretty scary rabbit holes.

 

[poconojoe]

Why not keep to the proven method that everyone has been using? Just build your walls, lay in your liner, tuck the excess liner under some nice flat cap stones and your good to go. If you feel the need, you can always pile more rocks and create a berm of soil up against the outside of the walls you created for more support.

The liner is there to keep the water in. No rocks, foam or any type of caulking is going to seal and hold back the water. Why even take that chance? You can easily empty your pond like that...killing your fish.

 

[MTguy]

I think if I drew this up it would be more clear what I was thinking about doing. I was considering putting a small (4’long x 18”wide x 16” deep) bog filter along my stream. The bog would actually be slightly deeper than the stream at the liner level, but I’m looking at building a wall to raise the water level in the bog high enough so that the water pumped into the 4” perforated pvc pipe would rise up through 12” of pea gravel/plants and then trickle over the rocks into the stream. I wasn’t set on the method I discussed, just thought it might be easier and look better. Worst case scenario would be that the water goes under the wall and goes straight to the stream rather than through the filter bed. If I get a chance to setup the laptop today I’ll draw out what I was thinking for reference. I promise I’m not crazy!

The reason I was looking to keep the rocks on top of the liner is I worried by the time I put a cap on wall I’d have a higher waterfall than I wanted.

 

[MTguy]

Forgot to add; I am taking your feedback. I didn’t want you to think I am arguing. At this point I’m just explaining what my original thought process was.

 

[addy1]

You are, in a way, making a barrier/partition bog, where the water seeps through the wall to get back into the pond.
Since the bog will be deeper than the stream, you could have a pipe, perforated, that pumped the water up into the gravel and out into the stream. The biggest issue would to make the wall tight enough to hold a lot of the water back and strong enough to hold back the gravel and water, a lot of weight. But if it did not hold a lot of water back, it would still flow though the pea gravel the plant roots, the wall and help with filtration.

The expanding foam does actually hold quite well, if your wall is wide at the base and creates a good solid base to build the rest of the wall up. I have some expanding foam I used 10 years ago in my stream to hold some rocks in place, it is still there still holding the rocks, Actually really hard to yank the rocks apart. All depends on how installed. Dry clean it might work well for you. Buy lots of cans, wear gloves that stuff is messy.

I have also used the pl roofing goop for where I do not want the water to get through that also has worked well for me. Again dry and clean and that stuff works.

 

[CSMcMullen1]

The start of my big

 

[MTguy]

I drew up a couple of pictures that would represent what I'm thinking of doing. I'm estimating the length of the bog at about 4' so I'll probably have 3 large boulders across the front holding things back. Here are the pictures. I forgot to add plants, but I'm sure you can use your imagination on that part.

 

[poconojoe]

I drew up a couple of pictures that would represent what I'm thinking of doing. I'm estimating the length of the bog at about 4' so I'll probably have 3 large boulders across the front holding things back. Here are the pictures. I forgot to add plants, but I'm sure you can use your imagination on that part.

Ok, now we understand what you are trying to do. The stream side can be built as you stated with the stones sitting on top of the liner. The water can now flow between the rocks and into the stream. However, the other three sides need to be built the conventional way, with the liner in front of and over on top of the stones to prevent the water from escaping.

 

[DerekOR]

I've read through this whole post once a couple of months ago, and probably forgotten just about 95% of what I've read. Apologies for asking some questions which I'm sure are covered and also I've probably already read.

I'm in the process of building a koi pond that is about 14 feet by 16 feet and 3.5 feet deep, and I will have a bog that is actually slightly larger than the pond by surface area. But - I want to do something a bit weird with my bog, and wondering if experts here think it will work out OK or if it will be a very bad idea. I plan to have the bog 20 ft x 20 ft with say a 15 ft x 15 ft deck centered in the middle of the bog. You will get to the deck by crossing a small bridge across the perimeter of the bog on one side. So, there would be pea gravel everywhere, but basically shade over most of the bog and just allowing plants to grow around a ~2.5 ft perimeter of the entire bog. One side of the bog will then flow into the main pond.

So the first question is, will the bog under the deck still function OK in terms of bio-filtration, or do you think it will plug up without plants to suck up the nutrients/muck? I am assuming plants will not grow much under the deck since there will be close to zero light under there. I am going to look into if I can make any sort of sections out of plexiglass just to get light in there, but not sure if that's realistic...

Second question is I want to have an effect where it looks like the deck is sort of floating. One will cross a small bridge to get across the perimeter of the bog and make it to the deck. So, I want to have maybe 2 or 3 inches of deep of water above the pea gravel around the edges of the bog to give that effect. Will water depth of 2 or 3 inches still allow plants to grow, or will that amount of water be too deep? I am a moron when it comes to anything there is to know about plants, so I'm hoping there are some nice type of plants that I can get which will survive in that amount of water. I'm about 1.5 hours south of Portland, OR. We have pretty mild winters (mostly rain). But it does freeze over just a bit from time to time...

One last question - since the deck will be a main seating area, will the bog smell at all? I wouldn't really want foul odors emanating through the boards of the deck when guests come over!

Thanks for any help or advice you can give .

 

[Lisak1]

Let me answer these in order:
1. Yes, the bog will function fine with plants in only some parts. The gravel also plays an important role in filtration as it gives the beneficial bacteria room to colonize and grow. I've read some opinions that the gravel is the most important component of a man made bog. But you may be surprised at plants that will find their way under the deck to grow.
2. Yes, water above the gravel is fine. Lots of plants will grow in 2 or 3 inches of water.
3. And no, your bog won't smell. If it does, then something is seriously wrong!

Your plan sounds very iinteresting! Can't wait to see you get started. You must have a nice big space for your pond. Make sure you take lots of pictures and start a thread here to post them. You'll be glad later that you did!

 

[addy1]

Welcome to our forum! @DerekOR

Start a construction thread and we will love following along on your build. That sounds really neat. The only thing I would do is watch the height of the plants. Some of mine grow 4ish feet tall. There are a lot of small bog type plants. I would almost do a water willow only bog IF I ever did it again. Which I never will. I love that plant, 12-18 inches tall and blooms almost all summer.

Creeping jenny, blue forget me not, you would have a great controlled bloom almost all summer. This is in my tiny bog planter for my small hot tub pond.

 

[mrsclem]

I would make sure to run manifold pipes under the deck area to keep that area from becoming stagnant.

 

[Lisak1]

I would make sure to run manifold pipes under the deck area to keep that area from becoming stagnant.

I agree with that! I understood the design to be ALL functioning bog, but just not all planted.

 

[GBBUDD]

I drew up a couple of pictures that would represent what I'm thinking of doing. I'm estimating the length of the bog at about 4' so I'll probably have 3 large boulders across the front holding things back. Here are the pictures. I forgot to add plants, but I'm sure you can use your imagination on that part.

that method is fantastic to soften the edges of the pond as you can have bog plants growing outside the "POND EDGE " I HAVE DONE THAT IN FOUR AREAS OF MY pond love it. it removes the look of a string of pearls first and foremost. and you can get quite creative.

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