Bog build

[mikeinpgh]

I plan on replacing my filter falls with a real bog. If I don't get to this project in the next couple of weeks it will be my spring project. I am going to use the retaining wall that I have to hide the preformed filter falls and make the whole area my bog, roughly 4'x3'. The bog will be between 12" and 18" deep. I also plan to fill the whole thing with lava rock and a ton of plants.

How do I run my plumbing through a rubber liner? Do you use a regular bulkhead fitting or is there a special fitting for rubber? Is to ok to use lava rock or should I just use pea gravel?

 

[addy1]

I would use pea gravel, better filtering and better for the plants. You can run your pipes through the liner, Shower drains work well with some additional goop i.e. the black roofing goop.

 

[mikeinpgh]

I'll have to go to Home depot and check out a shower drain. I can't picture what the seal looks like.
Am I able to use the bulk head fittings I already have or won't they seal properly in the rubber liner?
Thanks,
Mike

 

[addy1]

I have not used a bulk head fitting, if you are worried about it sealing well, put a layer of the pl black roofing goop, let it dry, I used it for my skimmer and it worked well, no leaks.

 

[Waterbug]

For EPDM I cut a hole 1/2 the diameter of the pipe, so 1" for a 2" pipe. The hole has to be pretty clean and accurate so I trace a circle using a Sharpe and a template. I cut the hole using a pair of curved blade scissors. Push the pipe thru, from the wet side toward the dry side and the liner stretches and pushes out along the pipe, laying down on the pipe giving you a place to put a hose clamp. No trick, it just does it on its own. I put the clamp on the dry side sealing the liner against the pipe. I also wrap the clamp in a strip of liner just to keep the liner from pushing against the metal clamp. Pretty easy, fast and cheap. I've done this using ABS and Sch40 PVC, 1.5" to 4". You don't want to use a thin wall pipe or a flexible PVC. I'm not sure if it would work that well for 3/4" pipe.

IMO there is only two ways to form a seal with EPDM liner. Pressure or chemical weld. EPDM is great gasket material so pressure works great. The chemical weld is only for joining the exact same materials so it doesn't work for pipes and EPDM. Goops may work well for many people, but there's no reason to expect them to work. Bubble gum could work too. I do know for certain that silicone doesn't work long term. For example, in the above instructions if you add silicone "just to be safe" you would introduce a potential leak long term because silicone forms a poor gasket compared to EPDM. Just my 2 cents.

However, my first choice would always be to design so the bog overflowed into the pond. I like simple.

Small point... "real bog" is not exactly accurate. A bog is acidic and so only specialised plants can survive in a bog. I know it's common in pond forums to use the term "bog" loosely, I certainly do, but adding the "real" could get you some suggestions that would be misleading. There was a time when I was into "true bogs" as we had to refer to them in forums. Keeping true bogs is a whole hobby in itself. I know there's no hope of changing the common use of "bog" in pond forums, and I'm not trying here, but when I talked to customers I always used the term "wet bed" as in "wet flower bed". My 4 cents.

 

[addy1]

I use the same method waterbug, but also add a small layer of goop, never have had a leak.

A bog is any area that is mainly dirt/gravel that stays wet.

"
A bog is a type of wetland characterized by a thick mat of partially decomposed plant material and highly acidic water. The conditions for bog formation are abundant in some regions of the Northern Hemisphere, which is where the majority of the world's bogs are found. In addition to being unique ecosystems, bogs have also been useful for humans for thousands of years, providing a source of fuel in the form of peat and food in the form of berries which grow on bog shrubs such as cranberries. Bogs also have cultural and religious significance in some parts of the world.
Bogs start out as slow moving rivers or ponds which are slowly taken over by sphagnum, a genus of moss which encompasses over 150 species. Cooler weather promotes bog formation, because the moss decays very slowly, sinking to the bottom of the bog while a layer of growing moss accumulates on top, restricting oxygen supplies to the lower water while also blocking heat. As a result, plant material decays very slowly, and the water becomes acidic.
Generally, bogs have poor drainage and no supply of fresh water other than rain. Over time, a bog will slowly fill in, creating ground on which shrubs and sometimes small trees can grow. A wide range of plant and animal species are adapted for bog living, including some lichens, turtles, berries, and carnivorous plants. Bog environments are also valuable because they can prevent flooding by acting as a buffer zone."

 

[Waterbug]

Addy, yes, like the definition you posted said, what makes a bog different from other wet areas is acidic water. Without that it's just a wet area. Not sure of the source but the definition is spot on.

 

[addy1]

Well my pond bog, is wet, the bog plants are growing great. The land bogs are wet and acidic, mainly because I built them with peat moss, and those plants are doing great.

So technically my pond bog is not a "true" acidic bog, but it is a bog, plant material, water, and great plant growth.

More of a bog filter, or split hairs call it a plant filter with gravel. But whatever it is called it works great.

 

[mikeinpgh]

I like the penetration/pipe clamp technique. I'm going to try it on a scrap piece of liner. Would the bulkhead fittings work though? That would be a pressure seal. :dunno:
The plan is for the "WET BED" LOL, to overflow into the pond through the waterfall I already have, modified of course.
My surface area is limited but, would it help to go deeper to incease the volume?
I'm still bouncing the idea of lava rock vs gravel. I don't know why I have lava rock stuck in my head.
Thanks for the great info. Keep it coming.
Mike

 

[Waterbug]

A bog by any other name would smell as sweet.

Bulkheads
Bulkhead fittings made for your liner material will certainly work very well. Using a shower drain also works when used as it was designed given manufacturer directions. Liner used in showers is very similar to pond liner. However, if the manufacturer says a specific bonding agent is needed it probably only works with specified materials. Pond liner can be clamped between a shower drain that screws together, and it does work. But its not as the manufacturer designed it. Most required the drain to be bolted to the floor and the liner kept in place with cement. This is true for all bulkheads to liner imo, keeping the both the fitting and liner secured makes the future trouble free. Not to say it moving around won't work. Just a question of risk.

I always try to design around holes in the liner. Like for a bottom drain I'll run the pipe inside the pond and out the side rather than thru the bottom. If the bulkhead fails going thru the side the only drops a foot or so.

Deeper Bog
A deeper bog has the advantage of taking longer to fill with silt. For effective filtering I don't think deeper helps. The main issue with these types of filters is channeling, where water really only travels through a narrow area and most of the filter never sees any pond water.

To that end I think making your own channels increases contact. For example, in a deep bed you could lay down 3" of gravel, then liner with an opening at one end, another 3", liner with an opening at the other end, etc. You can force the water to take a very long path. In addition to horizontal layers you can divide the bed vertically as well. There's no end to the pattern.

But you can't kid yourself into believing water will take the path you want. It will take the easiest, fastest path. So these types of deals have to be well sealed. There's not that much water going thru these so a small leak defeats the whole system. For that reason I like what is basically a stream filled with pea gravel, I'm sure the water is taking the entire path. The stream can be channels in a rectangular area, or around the entire edge of the pond, or around the edge of the yard. No end to this pattern either. Also easy to clean out.

Algae is particularly susceptible to antibiotic attack from bacteria when put into a long ride in close contact with bacteria while in the dark. The clearest ponds I've ever seen had really large (long) bog type filters. But I've also seen some poorly designed and didn't help much.

Lava Rock vs Pea Gravel
Lava rock has the advantage of more surface area and being lighter than pea gravel when dry. I think the little openings fill up pretty fast with silt and just as heavy when wet. Lava rock is more abrasive. Where you will really notice the difference is when it's time to clean out the bog. You may never get to that point, but if you do you will find pea gravel is many times easier to shovel out of the bog. Lava rock kind of interlocks and is one of Dante's rings.

Lava rock works better imo in a trickle filter where it is continuously washed clean of silt. Although even there I like pea gravel.

 

[mikeinpgh]

Good info. Thank you.
This is going to be a relatively inexpensive project except for the plants. I can never find cheap plants, only at the end of the summer.
Does anybody have any other tricks or info that would make this project more efficient?

I tried your liner penetration idea on a scrap piece of liner. Looks pretty good. I took a couple of pics.

The pipe shoved through. I didn't think it would fit.


The clamp. There wasn't a lot to clamp to but I think it was just enough. Make sure you are using stainless clamps.


A shot from the dry side. It looks like a clean and effective seal.



Thanks again,
Mike

 

[taherrmann4]

Mike,
Did you use any other sealant around the pipe? Doesn't look like it.

To be sure you don't have a leak I would take the side in pic 3 and make a bowl out of the liner, then pour some water around the pipe and let it sit like this and see if any water drains through on the other side. If this makes any sense.

 

[Waterbug]

You have it. Yeah, always just enough liner for the clamp.

I put the clamp on the dry side. Stainless steel isn't impervious to corrosion. You may also want to make sure the entire clamp is stainless steel. I've run into many where the band is stainless but the screw isn't and rusts. But the screw is thick and so even with rust will last a long time.

And I like the clamp protected so I can't hit it with a vacuum or whatever and the fish can't get cut although it's easy enough to wrap with strips of liner. But I'm sure the clamp on the wet side will work for many years.

For others trying this...yes, not super easy to get the pipe though the hole. I sand down the end of the pipe so it's rounded which makes it a bit easier.

 

[mikeinpgh]

Mike,
Did you use any other sealant around the pipe? Doesn't look like it.

To be sure you don't have a leak I would take the side in pic 3 and make a bowl out of the liner, then pour some water around the pipe and let it sit like this and see if any water drains through on the other side. If this makes any sense.

Waterbug says you don't need any sealant. But I did think about giving it a test with some water.

Cool, so I did it right.
To make the pipe go through easier I just put a little spit on the liner. :wink:
Protecting the clamp is a good idea. I wouldn't want to puncture the liner accidentally.

 

[addy1]

I always over do my seals, a little black goop helps seal beautifully, in addition to the way you did it above.