2 Types of DIY Bog filters - 12 inches of pea gravel or 3 foot of large medium small rocks?


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The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.


The more I research building a wetland/bog filters the more confused I get. I'm looking to turn a pool into a pond, it will be about 3000 gallons and the area I have set aside for the bog is approx. 36 inches deep and 20-30% of the area of the pond. I'd like to have the option to take a dip in the pond if possible. Not so much an all out recreation pond, but I'd like the option if I can get away with it. This is why I was following the Aquascape style since it has so much documentation as being used for recreation/swim ponds.

I initially was going to follow this DIY article I found. http://www.bogfiltration.com/making_your_own_upflow_bog_filte.html It is essentially the aquascape method, but without aquablocks and a DIY centipede and snorkel out of Drain pipe. I was going to use 8 inch double wall drain pipe and a 14 inch drain pipe chimney. Then the layers of large medium and then small rocks. I can't seem to find much on this method that doesn't involve the aquablocks (which I can't afford).

The more I read, I then came across this method, that seems to have a lot of support (some on this sub) and the author themselves say it will work with a pond my size. It is cheaper and easier than the previous method. They even mention that the number one mistake people make in bog filters in making them too deep?

https://nelsonwatergardens.com/gravel-bog-filter-construction/ Highlights of this method: 12 inch deep, all pea-gravel, 2 inch pipe in a grid style pattern at the bottom.

Then there is the Aquascape method. That has a pre-fab 12 inch bottom drain and a 14 inch clean out chimney. They call for a layer of aquablock and a layer or large rocks, layer of medium rocks and then a layer of small gravel. These wetland filters are typically three to four feet deep.

Does anyone have any advice on which I should pursue? I can't afford the amount of aquablocks or the prefab equipment I would need to do it their way. I was thinking I could get away with the Drainpipe DIY method without the aquablocks, but now I am second guessing myself. I hate to spend the extra money on the depth and extra couple tons of rock if all I really needed was 12 inches of pea-gravel to achieve the same results.
 
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Several members have used the aquablocks system, maybe some did the DIY aquablocks also. I went with the 12” pea gravel so can only advise that on the whole, I’m happy with the results and don’t see a need to have done it differently. I think the problem comes with either using a bottom drain (no no for 12” simple bog) , or, and I don’t have a skimmer but do know someone that does but that goes to separate water fall and like most of us, draws water from 8 to 12” from the bottom to feed the bog.
Bottom drains really need to be equal pressure feed to a cistern and it’s my opinion that is why the aquablocks system gained popularity as bottom drains just don’t work with the simple type of bog.
 
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Read addy1s thread on big building. She went a bit deep, but it works.
 

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I have had a small DIY “satellite” bog connected to my pond. It was the typical bog with a PVC pipe manifold under 12+inches of gravel. Waiting now to have a new pond done (we moved), and am pretty settled that I will use the Aquablocks, centipede and snorkel system.
 
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I have the 12" pea gravel style and my water is crystal clear. I used addy's guide as my inspiration. I have read the Nelson Water Garden article you referred to and it's pretty much on par with addy.

I can't attest for the Aquascape method, but there are some here that have gone that route. There are other things you can use besides the genuine Aquablocks, there are cheaper versions. Some have gotten creative and used the old plastic milk crates or the plastic cases they ship soda bottles in.

As I said, my water is crystal clear. Never in the many years of ponding has it been this clear. My bog surface is maybe a bit larger than 30% of my pond's surface.
 
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Thanks for the replys and warm welcomes. I took advantage of the holiday weekend and rented a jack hammer and went to work on the concrete patio around the pool. I've filled about halfway up the space i had set apart for the bog, so there is no going back now. I'm going with the 12 inch of pea gravel style.
 
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Thanks for the replys and warm welcomes. I took advantage of the holiday weekend and rented a jack hammer and went to work on the concrete patio around the pool. I've filled about halfway up the space i had set apart for the bog, so there is no going back now. I'm going with the 12 inch of pea gravel style.
Wow! A jack hammer! That's serious!
Don't forget to throw up some pictures of your progress.
Post up any questions you might have as you start getting it together.
How big is this bog going to be?
Here's some pictures of my bog add-on this Spring:
20200425_114119.jpg

20200425_162307.jpg

20200428_140727.jpg

20200504_101610.jpg

20200620_122421.jpg

As you can see, the water in my pond was solid green before starting up the bog. It is now crystal clear.
 
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This is our first season with our 12 inch gravel bog, styled like @addy1 and Nelson's Water Garden. We're very pleased with it. The only advice I can offer this early in the game is to include a clean out pipe in case it clogs. I'm planning on using it to divert water from the pond when we first start it in the Spring, in case there is any anaerobic bacteria build up over the winter.
 
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This is our first season with our 12 inch gravel bog, styled like @addy1 and Nelson's Water Garden. We're very pleased with it. The only advice I can offer this early in the game is to include a clean out pipe in case it clogs. I'm planning on using it to divert water from the pond when we first start it in the Spring, in case there is any anaerobic bacteria build up over the winter.
Yep, the clean-out stack is nice to have.

I built my bog this Spring. It has been running about two months now.

In the first few weeks I had to open my (two) clean out stacks a few times because the return water had slowed down considerably.

I think it was because the bog was new and my pond water started out murky and green.

I haven't had to do this for a while now. I think it's because the water is so clear and clean now.

I wouldn't build a bog without the clean-out stacks. It's better to have them and not need them than to need them and not have them. Plus, PVC pipe and fittings are so cheap and easy to work with.
 
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The aquascape design is my preference but I do have both. its hard to believe how clear the water is and each year it just gets better and better. you can find my build at the blue link below this posts .
 
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@poconojoe I read with interest you opened your clean out stacks a few times in the early days. I think that is what we're experiencing , but it is improving and you're right...the pond water is very clear !
 
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@poconojoe I read with interest you opened your clean out stacks a few times in the early days. I think that is what we're experiencing , but it is improving and you're right...the pond water is very clear !
Yeah, I turn off the pump, unscrew the cap on the stack, jamb a piece of scrap 1-1/2" flex PVC into the pipe, turn on the pump and shoot the water into a flower bed. The water comes out black for a few seconds, then turns clear.
 
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I think a bog will work whether it's 12 inches deep or the full on Aquascape style. Ours is the latter style and is four feet deep. One difference I'm just learning (8 years after building our bog) is the the void space at the bottom allows for sediment to settle, if the water flow is slow enough. I don't know that we actually HAVE any sediment build up in our bog, since we are pumping clear water into it and we've never had a reason to check.

And although our bog is four feet deep, the gravel bed ends up being only about 1.5 feet deep over the Aquablox and bigger rock that comprise the bottom portion. So I think both systems are the same in that respect.
 
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Thanks everyone. Here is the most current picture. You can see the Bog on the left. The drawing is crude, but it's the best i could get out on paper. ha
 

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Wow! A jack hammer! That's serious!
Don't forget to throw up some pictures of your progress.
Post up any questions you might have as you start getting it together.
How big is this bog going to be?
Here's some pictures of my bog add-on this Spring:

As you can see, the water in my pond was solid green before starting up the bog. It is now crystal clear.
Thanks for the picture, that is very helpful. I'm planning on doing my plumbing very similar.
 
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something else/modification to think upon;

I did more or less, the aquablox system without the aquablox. From what I garner, the Aquascape parts can be pricey so maybe this will be more palatable. What I used was 4" corrigated drain pipe and cut the slits in that. This pipe is cheap and with 4", affords more area to both slow the water as well as not get clogged so easily. For the 'vault/snorkel', I WAS going to use 12" drain pipe cut to size but the price, again, seemed high so I rummaged around and made my own using plastic buckets with the bottoms cut out. When I revamped my pond, I decided to dual purpose this 'vault' mechanism in the form of using a 30 gallon trash can with 4" holes (4 of them) cut out of the sides neare the bottom. Putting this then at the lowest point of my bog means anything accumulating will be accessible for pumping out. When not in use, it now doubles as a place to grow a pot of water iris. So, in bog v1, I had the pond tube hooking up to 4" manifolds (the drain pipe) and that to the homemade snorkel. In bog v2, I ran two 4" lines at the bottom of my bog and because I wanted the iris to be in a specific spot, did not connect manifold to my new trash can vault. It won't matter because IF I ever have to flush the manifolds or bog proper, everything will end up at the bottom of my new iris/trashcan snorkel. I like the trashcan idea because it is much easier (wider) to get a pump in and out of.

And like the Aquascape system, I used large boulders (6-8") along side and one layer over top my manifolds, then followed it with about 12-18" of 2" river rock, and lastly by 12" of peagravel (3/8").

I'm only posting this so you can see you don't need to spend big $$ to get a more/larger system. I went from a 4'x4'x40" bog to a 23'x3'x3' version because I nearly tripled my pond volume.

Just adding more fuel to your fire...
 
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something else/modification to think upon;

I did more or less, the aquablox system without the aquablox. From what I garner, the Aquascape parts can be pricey so maybe this will be more palatable. What I used was 4" corrigated drain pipe and cut the slits in that. This pipe is cheap and with 4", affords more area to both slow the water as well as not get clogged so easily. For the 'vault/snorkel', I WAS going to use 12" drain pipe cut to size but the price, again, seemed high so I rummaged around and made my own using plastic buckets with the bottoms cut out. When I revamped my pond, I decided to dual purpose this 'vault' mechanism in the form of using a 30 gallon trash can with 4" holes (4 of them) cut out of the sides neare the bottom. Putting this then at the lowest point of my bog means anything accumulating will be accessible for pumping out. When not in use, it now doubles as a place to grow a pot of water iris. So, in bog v1, I had the pond tube hooking up to 4" manifolds (the drain pipe) and that to the homemade snorkel. In bog v2, I ran two 4" lines at the bottom of my bog and because I wanted the iris to be in a specific spot, did not connect manifold to my new trash can vault. It won't matter because IF I ever have to flush the manifolds or bog proper, everything will end up at the bottom of my new iris/trashcan snorkel. I like the trashcan idea because it is much easier (wider) to get a pump in and out of.

And like the Aquascape system, I used large boulders (6-8") along side and one layer over top my manifolds, then followed it with about 12-18" of 2" river rock, and lastly by 12" of peagravel (3/8").

I'm only posting this so you can see you don't need to spend big $$ to get a more/larger system. I went from a 4'x4'x40" bog to a 23'x3'x3' version because I nearly tripled my pond volume.

Just adding more fuel to your fire...
Thanks for this info @brokensword Would love to see what you have done. I was going to use a pool sand filter for a vault. I also found some 8" corrugated drain pipe that I can use. @brokensword can the 4"pipe handle such a load of stone without it being crushed? That is my concern about the drain pipe.
 

brokensword

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No problem with the weight as I put large stones around the tube and then over top so the load above is actually resting more on the 6-8" stone. When I dug up bog v1, the drain pipe was just fine.

Here's some pics showing bog v2 construction; I have two pumps sending water to 2 prefilter barrels, which then dump into the bog. The water rises up through and flows over my weeping wall and back into the pond.

190517 - prepping for bog 1.jpg

190518 - pond2 build - framing bog 1.jpg
190528 - pond 2 build - filling 1.jpg
190603 - pond 2 build - 01wfall wall.jpg
190603 - pond 2 build4 - 4 bog layer 1 rock 3.jpg
190603 - pond 2 build6 - 6 bog layer 2 rock 2.jpg
190604 - pond 2 build - bog layer 3 rock.jpg
190619 - b2 4.jpg
190623 - b2 6.jpg
 
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Thanks for the photos @brokensword, helps a lot seeing what you have done. Also, great work!
Looks like, you don't have to worry about snow, as it looks like the entire pond is covered. :)
 

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