Bog Filter Issue.

[Demon44]

So I built my bog filter. As recommended I have 2 lengths of PVC pipe to supply water. It is an "upflow". Pipes have a series of linear cuts along the top and are covered with app. 12 in. of 3/8 pea gravel.

At the far end of the pipes I have added vertical cleanouts which are capped off.

Water flows into bottom and to the 2 pipes via a T connection. After flowing up through the gravel water exits back into pond via outlet at top.

So here is my issue and I really am at a loss.

The water seems to only flow from the pipes at the far end (below the cleanouts).

I have a ball valve and if I open it fully it is clear that there is flow up through the gravel but NOT at the end of the pipes closest to the inlet. If any thing I would have thought that more water would flow out closer to the inlet than the outlet. Any thoughts as to why I have no flow at the beginning of the distribution pipes?
Makes little sense to me from a hydrological/pressure point of view. Yes I do have cuts along entire length of pipes. Slits are narrow enough so no gravel can clog them

FWIW: I did remove the caps from the cleanouts and a bit of junk flowed out but made no improvement to the lack of water flow closest to the T where my 2 pipes diverge.

Oh yes I seem to have equal flow from both pipes just not at the near end of the bog?

Anybody??

 

[Laaf]

How do you know it is only flowing out of the far end? You made the linear cuts. There is no way water is not flowing out of them along the entire length of pipe. Maybe it just appears it is only flowing from the far end since there is water flow most noticeable from there.

 

[j.w]

@Demon44

 

[addy1]

Mine appears to do the same. But when it is shut off the level drops right below the gravel, when turned on you can see water coming up everywhere.

 

[drjay9051]

You both may be right. It's just that I see it well enough at the far end. And if their near end it seems somewhat stagnant. I'll shut it down and see how it rains and fills again. It may just be an optical illusion. I'm probably over thinking this.

 

[drjay9051]

You both may be right. It's just that I see it well enough at the far end. And if their near end it seems somewhat stagnant. I'll shut it down and see how it rains and fills again. It may just be an optical illusion. I'm probably over thinking this.

Admins, you may have noticed that the post was from another name. What happened is? I'd forgotten all my info. So I re-registered under another account on another email. However, I am the same person I will use Doctor j from now on. Hope I haven't caused any confusion.

 

[GBBUDD]

@drjay9051 If you think about it the answer is actually quite simple. you have two pipes cut the same from the simple splitter, with the same amount of slits right? these slits are restricted by the gravel . Now one step in the peastone bogs that people often omit, which i don't understand, is the graduation of layers of sized stone. It sounds like you just added the 3/8" thus there is restriction to the flow getting out of the pipe so the water travels down the pipe to where it hits the end and the pressure will build. thus your cuts at the end get more pressure first and they will leach more than the others.

Good news is the stone will start to clog slightly and the water will look for the path of least resistance thus the slits that were toward the beginning of your pipe will eventually b that least resistance and then your bog will even out.

The graduation of stone from 2 to 3" to 1 to 2" and 3/4 is crucial imo This allows for that uneven pressure to even out throughout the bog .

But again rest assured your bog will even it's self out in time

 

[Mmathis]

Hello and welcome!

Just out of curiosity, what are the dimensions of your bog? You say you cut your slits small….is it possible that they are too small?

Pictures might be helpful, as well.

 

[j.w]

@drjay9051 I think @addy1 may be able to combine your posts to the name you choose but I'm not positive.

 

[drjay9051]

@drjay9051 If you think about it the answer is actually quite simple. you have two pipes cut the same from the simple splitter, with the same amount of slits right? these slits are restricted by the gravel . Now one step in the peastone bogs that people often omit, which i don't understand, is the graduation of layers of sized stone. It sounds like you just added the 3/8" thus there is restriction to the flow getting out of the pipe so the water travels down the pipe to where it hits the end and the pressure will build. thus your cuts at the end get more pressure first and they will leach more than the others.

Good news is the stone will start to clog slightly and the water will look for the path of least resistance thus the slits that were toward the beginning of your pipe will eventually b that least resistance and then your bog will even out.

The graduation of stone from 2 to 3" to 1 to 2" and 3/4 is crucial imo This allows for that uneven pressure to even out throughout the bog .

But again rest assured your bog will even it's self out in time

I appreciate your reply. So everything I read told me to use just straight 3/8 pea gravel. I do see your logic. I can either go through the labor of rebuilding the bog ut I think I'm going to take your advice and just wait it out. I do have good plant growth. So I think I'm going to be okay again. I appreciate your knowledge

 

[drjay9051]

Hello and welcome!

Just out of curiosity, what are the dimensions of your bog? You say you cut your slits small….is it possible that they are too small?

Pictures might be helpful, as well.

Turtlemommy:
I used 1.5 in. Schedule 40 pvc.
I do not believe the slit are too small either width wise or length wise.
They were cut using a power miter saw and are the width of the blade.
I would say the average cut Is halfway through the pipe.
The cuts are fairly evenly spaced.

Bog is small, a 300 gal stock tank say 3x4.5 ft

 

[Lisak1]

@drjay9051 welcome!

I believe @GBBUDD nailed it - the water is traveling the easiest path until it cannot move horizontally anymore and is forced to go upwards. I do believe it will all work itself out. If not, 12" of pea gravel isn't that much to dig out. My bog is 4 feet deep!

If you read to only use pea gravel, you weren't reading here!

 

[Demon44]

@drjay9051 welcome!

I believe @GBBUDD nailed it - the water is traveling the easiest path until it cannot move horizontally anymore and is forced to go upwards. I do believe it will all work itself out. If not, 12" of pea gravel isn't that much to dig out. My bog is 4 feet deep!

If you read to only use pea gravel, you weren't reading here!

Lisak1
Actually I did read it on this forum. Please look at Addy1 write up on bog construction.



I also read to use "3/8 pea gravel. End of story"
This comes from the following site which I was advised is a quality source of information

Build an Active Gravel Bog Filter | Nelson Water Gardens and Nursery

nelsonwatergardens.com

I suppose we all have different methods.

 

[Lisak1]

@addy1 is an anomaly... haha, sorry Addy! - although her bog does function beautifully, you have to remember it is huge. It runs the length of her pond and is deeper than 12 inches. And she doesn't just have "a pond" - she has a series of connected ponds that all function as a whole.


Can you use only pea gravel? Sure. But so much has advanced in the world of garden ponds. The idea that your bog can benefit from void space is relatively new for example.

I'm familiar with the site you referenced - they have not updated that information in many many years. I first read it 14 years ago and it's the same now as it was then. Is the method still good? Sure. Is it the best? Maybe not. One thing we have all learned who hang around here for a long time - there are many many ways to skin the cat. Lots of things can work, but you have to consider all the variables. Here are two:


Where's your pump located?

Do you pre filter your water?

 

[Lisak1]

On a side note - is anyone having trouble typing on this forum? I'm having issues with whole sentences disappearing or text writing over other text. Very bizarre.