Bog; above or below pond?

[islandboy]

I discovered this forum after I had built our pond/mini-bog/stream. Trees and slope dictated the design.

It seems most bogs are above the pond and pumps are in or beside the ponds. Is this a hard and fast rule?

Having expanded my knowledge I am considering a larger bog:

 

[combatwombat]

There’s no requirement that a bog be above the pond. It’s just the most convenient way to build it for most people.

If I’m understanding your water flow correctly, I think it’s a totally clever design. Only concern is that you’re sending water w/o any mechanical filtration into the bottom of your bog. Not the end of the world for a small, shallow bog like yours, but might increase maintenance and reduce efficiency of the bog.

You might consider splitting the feed line from your pump and pumping into the bottom of the bog directly from the pump before the water has a chance to pick up solids while traveling through the pond. The water from the pond could just flow over the top.

 

[poconojoe]

A little unconventional, but I see your dilemma. Your pond is at the high point in the system.
If it's functioning well as is, why change it?

There are so many bog builds that have broken the so-called rules and they work just fine.
The goal is filtering the water and if your original design is accomplishing that, why not leave it?

Here's what I see, for what it's worth...

In your first drawing, water is being skimmed off the surface of the pond, not being pumped from the middle or near the bottom. So, basically you have created a big skimmer.
That might be what you want, I don't know.
Maybe if the water entering the pond has enough volume to stir things up, it might help.

In your upgraded version, what is the purpose of the perforated pipe? It looks like it's just sitting there doing nothing, unless I'm missing something or I'm misinterpreting the drawing.

You are pumping the water into the bottom void and it flows up from there.
How will you create that void? Some sort of shelf to support the gravel?

Most of us pump the water from near the bottom of the pond to the bog. Then through the perforated pipe and it rises up through the gravel. No void.
Some people use a snorkel and centipede instead of the perforated pipe.

I'd leave it if your water is clear, unless you are having other problems.

 

[Lisak1]

I am a little confused about the original - if you're dumping water to the top of the bog, it's not really going to function as such. Am I understanding what I'm seeing? If so, then I endorse the bigger bog plan! (Well, I'd endorse a bigger bog no matter what, but you get the point!)

 

[combatwombat]

I am a little confused about the original - if you're dumping water to the top of the bog, it's not really going to function as such. Am I understanding what I'm seeing? If so, then I endorse the bigger bog plan! (Well, I'd endorse a bigger bog no matter what, but you get the point!)

It looks like there is a baffle ahead of the bog. So water off of the pond falls underneath the bog and then rises up. Kind of like a negative edge.

 

[islandboy]

Thank you for your input.
The purpose of the perf pipe is to expand the area of water flow into the gravel.
In both the existing and planned bogs the water enters in a lower void, then pushes up through the pea gravel. It was designed to be a skimmer and there is an easily cleaned screen before the falls into the bog for fish and large debris. Water returns to the pond through a waterfall (1/3rd) and an under-gravel filter in the deep end (enhanced with vigorous aeration).

 

[poconojoe]

Thank you for your input.
The purpose of the perf pipe is to expand the area of water flow into the gravel.
In both the existing and planned bogs the water enters in a lower void, then pushes up through the pea gravel. It was designed to be a skimmer and there is an easily cleaned screen before the falls into the bog for fish and large debris. Water returns to the pond through a waterfall (1/3rd) and an under-gravel filter in the deep end (enhanced with vigorous aeration).

I still dont get the purpose of the perforated pipe. Is it just sitting there?
Some people use aqua-blox or plastic milk crates. I'm thinking your using the pipe in a similar manner.

 

[islandboy]

I still dont get the purpose of the perforated pipe. Is it just sitting there?
Some people use aqua-blox or plastic milk crates. I'm thinking your using the pipe in a similar manner.

Exactly. The 8" pipe (centipede) is for detritus to collect where it can be flushed out (sloping ground advantage). The water then spreads up into the perf pipe (aqua-blox), then the pea gravel.

 

[brokensword]

Exactly. The 8" pipe (centipede) is for detritus to collect where it can be flushed out (sloping ground advantage). The water then spreads up into the perf pipe (aqua-blox), then the pea gravel.

You're going to have to be careful you don't run your pump dry with this plan since it depends on being supplied by the bog. If the flow slows like say from clogging, you will starve the pump.

 

[brokensword]

Exactly. The 8" pipe (centipede) is for detritus to collect where it can be flushed out (sloping ground advantage). The water then spreads up into the perf pipe (aqua-blox), then the pea gravel.

I too am using the larger drain pipe/tile to slow the flow a bit, so I understood your intent. Don't use the perforated type, use unperforated and cut 1/3 down through with a circular saw for your water egress.

 

[Katemort]

I'm sorry, I'm clueless and looking for help myself. My partially above ground pond is overstocked at 660l with 4 x 6to 7 in goldies who I don't want to part with and am having water quality issues. I'm therefore considering building a bog filter. There isn't room to build a bog filter in the ground. Ideally I'd like to find a sturdy enough container, ideally 30cm wide, 150+cm long and as deep as I can find without it toppling over to fit space along top of pond. (Hoped to find something suitable, drill an inlet hole and use an old tap as a waterfall into the pond, don't know how feasible that is, has anyone done something similar)? I've looked at galvanised animal feed and water troughs but can't find any that size, narrow ones are too shallow. I've also looked at plastic barrels and water tanks, for example, like used for caravans but partner will moan about appearance of it. That would also have to go at ground level. Pond is 40cm/16 in above ground but from previous posts that could work? Any advice at all hugely appreciated, am at a loss! Thank you

 

[poconojoe]

Don't use anything galvanized unless you cover it with a liner. The zinc in the galvanizing is bad for the fish.
Mostly anything else that will hold water will do.
People have used stock tanks, window box planters, preform plastic ponds, wooden built boxes with a liner, anything you can imagine.

If it will be your only filter, make sure it's surface area is at least 30% of the pond's surface area.

Any additional questions, just ask.

 

[poconojoe]

If you drill any inlet or outlet holes in your bog container, use bulkhead fitting to seal the connection. They are the best way to seal it, hands down.
They come either threaded or slip (glue) connections.

 

[Katemort]

Amazing, thank you!

 

[GBBUDD]

The problem with the bog with a gravity fed water supply is there is no pressure to force the water up through the gravel and as it starts to fill/ clog there is no pressures to flush the next path of least resistance. It appears you have about a foot of drop but the water coming back up that foot means there is no head pressure. water weighs 8 pounds per gallon but that weight equals out if the water on both sides are at the same height . will water find its way out and through yup until that area that has the least resistance is up and over the divider. don't get me wrong your design will work but it has no pressures to make the bog filter the pond . do you have a fantastic little hover time in your bog where particles will get left behind out of the water column heck yea but that's when clogging will start. but your plants will do just fine.