Pea gravel bog question

[Pond skipper]

This question is a bit late being asked because I didn't know about this forum until recently and I already did this.. just want some opinions...I made a pea gravel bog filter area that my waterfall falls into.. I was too scared to cut a hole in my beautiful new EPDM.. so I didn't use the usual (from what I can see on YouTube..) PVC frame on the bottom and feed the water from there up through the gravel.. instead I figured that it should still work basically the same if the water flows from back to front instead of bottom to top.. so my waterfall drops the water in at the back of the bog and that should force the bulk of the water through the gravel horizontally instead of vertically.. before it spills back into the main pond. I know that some of the water might just "ride" over the top of the gravel but I think much of it travels below the gravel top as well.:. is my thinking wrong on this... And no I didn't think about running a hidden pipe over the side and down to the bottom of the bog to get it to that under gravel PVC frame until just yesterday.. don't want to dig all that gravel out now..lol

 

[Mmathis]

I think that up-flow blogs tend to be more efficient (and you don’t have to cut the liner), but many people have success with what you are talking about. @addy1 has tried it both ways, so maybe she’ll give some input.

 

[addy1]

The biggest problem you might have is the dirt, debris, will build up on top of the gravel. The water won't flow down into the gravel just over it.

One of my first builds, long ago, I did that. It constantly got covered over with muck and overflowed. Since I had it built it had to flow through the gravel to get out. Instead it flowed over and out.

Maybe make a hole, push the gravel away with a wire screen or something, that the water falls into. Might make it flow more though the gravel instead of over.

 

[qclabrat]

This question is a bit late being asked because I didn't know about this forum until recently and I already did this.. just want some opinions...I made a pea gravel bog filter area that my waterfall falls into.. I was too scared to cut a hole in my beautiful new EPDM.. so I didn't use the usual (from what I can see on YouTube..) PVC frame on the bottom and feed the water from there up through the gravel.. instead I figured that it should still work basically the same if the water flows from back to front instead of bottom to top.. so my waterfall drops the water in at the back of the bog and that should force the bulk of the water through the gravel horizontally instead of vertically.. before it spills back into the main pond. I know that some of the water might just "ride" over the top of the gravel but I think much of it travels below the gravel top as well.:. is my thinking wrong on this... And no I didn't think about running a hidden pipe over the side and down to the bottom of the bog to get it to that under gravel PVC frame until just yesterday.. don't want to dig all that gravel out now..lol

how deep is your bog? I suggest biting the bullet and start digging. The plumbing work is very easy to do, mine has gravel about 1/3 of the way filled on the bottom before the PVC so you may not need to completely empty it if you have enough height for the plant roots. The water is cleaned by the roots of the bog plants, IMO it defeats the purpose of having a bog otherwise.

 

[Lisak1]

I concur with the opinions already shared - an upflow bog is far more efficient than an overflow. A downflow works IF the water is flowing all the way through and out the bottom. Our pond essentially flows into a downflow bog - we have a 1000 gallon rain exchange at the outflow end of the pond. But as @addy1 said, with a downflow bog you have issues with debris and muck building up and needing to be cleared or the water will just flow over.

You don't have to cut liner for an upflow - the plumbing can run down the side of the bog inside the liner to the plumbing at the bottom. That's how most I've seen are set up. I've seen a few built with bulkheads near the bottom, but those are often bogs with exposed backs or sides. Mine is 100% in-ground.

 

[ShawnInfirmity]

If I did my "bog" over again I would do an upflow bog for sure!! One day I might bite the bullet and clear it all out down to the liner and plumb in some PVC and replace the gravel and plants but I already know that's gonna make a HUGE mess but at least it should be a temporary mess.

 

[Lisak1]

I already know that's gonna make a HUGE mess but at least it should be a temporary mess.

What fun is it if you aren't making messes?

 

[Mmathis]

If I did my "bog" over again I would do an upflow bog for sure!! One day I might bite the bullet and clear it all out down to the liner and plumb in some PVC and replace the gravel and plants but I already know that's gonna make a HUGE mess but at least it should be a temporary mess.

Mine (my small “turtle bog”) has always been an up-flow, but after a couple of years I wasn’t happy with it. Last year I ripped it all out and started over (redid the manifold). People often ask what is the best size for the PVC manifold..... Because I have a small-ish bog, I used (I think) 1-1/4” PVC. Eh, small space/small tubing, right? NOT! I replaced that with 2” PVC and that has made all the difference! And boy, I hope I NEVER have to go through that process again — carting out, cleaning, and temp. storing, then re-installing the pea gravel was backbreaking and almost as much work as digging a 3000 gallon pond!! (but, then, my bog is contained within my turtle habitat, so I had space constraints which presented its own problems.)

 

[Pond skipper]

Thanks all , for the insights..Addy I Had originally planned to do exactly that.. build in a frame to keep the gravel back from where the water falls to but list my mind.....er ...changed my mind, for some reason I don't remember... I have been thinking of doing that now.. maybe next year start over and go with up flow...