DIY Bog

[tarry]

Or the components you use. We used Aquablox and a snorkel and centipede, but it could have been built much cheaper if we wanted to do a DIY version.

Hi all. I am building a bog, and have a few questions, related to DIY. I am converting an old swimming pool - we filled it halfway with broken concrete and gravel, then put in a new floor, so it is now 3-4' deep. About 1300 SF. I'm going to put in a 20x13' bog. I'll start with a layer of milkcrates, then a thin layer of perhaps fist-sized rock, then a foot of gravel. I was thinking about how I would distribute the water -- a DIY version of the centipede. The more I think about it, the less I think I need to do anything at all! If I have a 10" thick layer of water (from the milkcrates), isn't that going to allow the water to fully distribute over the entire area? The difference in upward pressure (forcing water through the rock layers) should be virtually constant across that entire milkcrate layer, right? So if I just run my pipe into that layer, do I need any further distribution system?


Separate question: I am worried that the gravel will fall down through the thicker rock. Is it reasonable to put in a layer of plastic mesh to help catch some of that, between the gravel layer and the fist-sized rock layer?

Thanks!

 

[Mmathis]

@tarry Hello and welcome! I am asking the mods to start this over as a separate thread for you…..since you have questions specific to your build.

I’m not sure if I’m answering your question, but one purpose of the upflow system is to have the water be in direct contact with the plant roots. This process will still happen with any type of system, but upflow is the most efficient.

As far as the plastic mesh goes, I guess it depends on how fine it is. You don’t want it too fine or the water will clog the mesh, but if it’s too wide, it might not hold back the pea gravel. If I’m not mistaken, the larger stones should work to keep the gravel in place.

Are you planning to have a barrier wall between the pond and bog sections?

Pictures might help us see better what you are planning.

 

[poconojoe]

Hi all. I am building a bog, and have a few questions, related to DIY. I am converting an old swimming pool - we filled it halfway with broken concrete and gravel, then put in a new floor, so it is now 3-4' deep. About 1300 SF. I'm going to put in a 20x13' bog. I'll start with a layer of milkcrates, then a thin layer of perhaps fist-sized rock, then a foot of gravel. I was thinking about how I would distribute the water -- a DIY version of the centipede. The more I think about it, the less I think I need to do anything at all! If I have a 10" thick layer of water (from the milkcrates), isn't that going to allow the water to fully distribute over the entire area? The difference in upward pressure (forcing water through the rock layers) should be virtually constant across that entire milkcrate layer, right? So if I just run my pipe into that layer, do I need any further distribution system?


Separate question: I am worried that the gravel will fall down through the thicker rock. Is it reasonable to put in a layer of plastic mesh to help catch some of that, between the gravel layer and the fist-sized rock layer?

Thanks!

Personally, I prefer simplicity.
What you're stating sounds way too complicated for me.
My bog is simple. 2" pvc distribution manifolds covered with smooth river stone. Period.

@addy1 Has been running her "simple" design for over a decade without any problems. That's good enough history for me.

But, it's your project and do as you please.
Keep us posted and take a bunch of pictures for yourself and to help others too.

 

[tarry]

@Mmathis Separate thread sounds good (wasn't sure what was proper, so I figured I'd go with the less invasive approach to start) -- thanks.



Definitely an upflow system. And definitely a wall. Here's a length-wise slice through the pond design:

The pool walls are a constraint -- can't change them. The gray wall divides the pond from the bog (not to scale; bog is about 20% of total area, about 20 x 13). Water is pumped in from the skimmer box to under the bog filter, percolates up and cascades over that wall. If I were digging this from scratch, I'd make the bog shallow. But the swimming pool walls are an unalterable constraint, so the bog is 2.5 to almost 3.5' deep. I don't want the gravel to be that deep, right? -- so I need filler material. That can be milkcrates (about $200 cubic yard to buy, light and easy to place) and/or large rock (about $65 / cubic yard to buy, LOTS of work to put in place). I'm thinking one layer of milkcrates, then rock. (The picure is not to scale. 11" of milkcrate + 12" gravel + 2" of water on top + another 1" to the top of the pool wall = 26", so the medium + large rock layer will range from 4 to 14".)

Now, in a typical aquablox design, there would be a centipede under the milkcrate/aquablox layer. The DIY version might be PVC pipe with slots cut in it, underneath (or in between) the milkcrates. My heretical idea is that, once you have an 11" water-filled space, you no longer need a centipede or a pipe; the milkcrates themselves distribute the water pressure evenly over the 'roof' of large rock, so the water should flow fairly equally through the entire bog.

I will probably put in a corrugated pipe over the deepest part of the bog so that I can lower a pump down in between the milkcrates and pump out and gunk that accumulates (not shown in the figure) -- though with the water intake from the skimmer box (which will filter out most leaves, etc) and a low fish:water load, I hope to go 2-5 years between cleanings.

thoughts? Thanks!!

 

[combatwombat]

Hi all. I am building a bog, and have a few questions, related to DIY. I am converting an old swimming pool - we filled it halfway with broken concrete and gravel, then put in a new floor, so it is now 3-4' deep. About 1300 SF. I'm going to put in a 20x13' bog. I'll start with a layer of milkcrates, then a thin layer of perhaps fist-sized rock, then a foot of gravel. I was thinking about how I would distribute the water -- a DIY version of the centipede. The more I think about it, the less I think I need to do anything at all! If I have a 10" thick layer of water (from the milkcrates), isn't that going to allow the water to fully distribute over the entire area? The difference in upward pressure (forcing water through the rock layers) should be virtually constant across that entire milkcrate layer, right? So if I just run my pipe into that layer, do I need any further distribution system?


Separate question: I am worried that the gravel will fall down through the thicker rock. Is it reasonable to put in a layer of plastic mesh to help catch some of that, between the gravel layer and the fist-sized rock layer?

Thanks!

I also used milk crates reinforced with 1” pvc. So far so good.

I made a centipede out of HDPE culvert pipe, but I do think you could get away without one. Probably helps with back flushing if you slope correctly, but maybe not totally necessary.

 

[tarry]

@poconojoe -- please see my reply to mmathis -- wasn't sure how to tag you both with the one reply.

 

[tarry]

I also used milk crates reinforced with 1” pvc. So far so good.

I made a centipede out of HDPE culvert pipe, but I do think you could get away without one. Probably helps with back flushing if you slope correctly, but maybe not totally necessary.

How did you reinforce the milk crates? Sounds like a great idea!! Did you cut a piece to size and placed it vertically in the middle of the crate?

 

[poconojoe]

@poconojoe -- please see my reply to mmathis -- wasn't sure how to tag you both with the one reply.

Your design seems good.
Not as complicated as I originally thought. The drawing helps to better describe it.

In reference to your concern about the container being too deep....
I will note that many here have bogs that are deeper than what is suggested and they work just fine.
I believe I recall someone having 4 feet of gravel because they just didn't have the room, so they went deeper.

I think the Aqua blox, snorkel and centipede setup is geared more towards a large pond, where as the simpler gravel directly over manifold distribution pipe design works fine for smaller ponds.

 

[combatwombat]

How did you reinforce the milk crates? Sounds like a great idea!! Did you cut a piece to size and placed it vertically in the middle of the crate?

A vertical support would have been much stronger, but couldn't easily think of a great way to protect the liner. Could have added a layer of rock first, I guess. Here's how I did it:

Technically speaking, under 2' of gravel, I don't know that you need any reinforcing at all.

 

[Jhn]

@tarry The centipede and snorkel setup arent for water distribution purposes, this is for settlement of silt and being able to access and pump it out. If you build it the way you have it drawn there is no way to clean it if needed. To me wouldn’t install this style system without it, very easy to diy both during the install, imo always better to have it and not need it than need it and not have it.

 

[poconojoe]

@tarry imo always better to have it and not need it than need it and not have it.

We have a similar saying in the electrical industry when it comes to the length of wire during an installation.
" I'd rather be looking at it than for it"

 

[Ian]

Hi @tarry, I've moved the question to a new thread for you .

 

[j.w]

@tarry