Bog filter questions

[ChrisK]

Hello All,

I've built a couple of ponds in the past, but all were mechanically filtered.
At our new house I'm building one and have just discovered Bog filtering.
This site looks like an Excellent place to get some good advice. Thanks in advance.
Pond will be about 1600 gals. Bog will be about 470 gals.
I will have fish in the pond (maybe Koi, but they outgrew my previous ponds, and are kinda destructive/messy). We'll see.
Bog will be at the top of a steep grade, and I would like to have a waterfall as well.
I've been researching this, and I have some questions. I'll list them below.
What is the best height difference between the bog walls and outflow for the bog?
Should I combine the bog output and the waterfall? (I'm trying to use one pump in a DIY skimmer), or would I be better off with 2 seperate pumps?
I've read about the flow rates for the bog which seem slow for a waterfall. I can send pictures if they will be helpful.
I'm sure I'll have more to ask after I get some of your wisdom on these first few.

Thanks again.

 

[combatwombat]

Welcome! Look forward to seeing your build!

What is the best height difference between the bog walls and outflow for the bog?

6" MINIMUM. Once plants grow in, you need a lot of sidewall/freeboard within the bog to keep it from overflowing.

Should I combine the bog output and the waterfall?

You can. Don't have to. You can split the output of the pump w/ ball valves and send however much you want to each.

would I be better off with 2 seperate pumps?

Not necessarily, but a second pump is good for backup. If one fails, it's not an emergency replacement.

I've read about the flow rates for the bog which seem slow for a waterfall.

You can fix this by splitting the output of the bog pump before it enters the bog. Send the reduced flow to the bottom of the bog and dump the rest out on top of the bog. Then you get the right flow to the bog and whatever size waterfall you want. This also gets you a siphon break that prevents the bog from back flowing into the pond during a power failure.

 

[ChrisK]

Welcome! Look forward to seeing your build!


6" MINIMUM. Once plants grow in, you need a lot of sidewall/freeboard within the bog to keep it from overflowing.


You can. Don't have to. You can split the output of the pump w/ ball valves and send however much you want to each.


Not necessarily, but a second pump is good for backup. If one fails, it's not an emergency replacement.


You can fix this by splitting the output of the bog pump before it enters the bog. Send the reduced flow to the bottom of the bog and dump the rest out on top of the bog. Then you get the right flow to the bog and whatever size waterfall you want. This also gets you a siphon break that prevents the bog from back flowing into the pond during a power failure.

Thank you, Combatwombat.
This is very helpful but begs another question.
If I do use a single pump (I do have a backup pump-thanks) won't the ball valves be under water?
My intention was to use 2" flexible PVC inside the system.
Thanks again for your help, and for the welcome.

 

[j.w]

@ChrisK
I think you would like to add Shubunkin goldfish as they are quite pretty and not destructive like koi. Your pond would be pretty small for many koi.

Shubunkin Goldfish, they come in many patterns

 

[Jhn]

Thank you, Combatwombat.
This is very helpful but begs another question.
If I do use a single pump (I do have a backup pump-thanks) won't the ball valves be under water?
My intention was to use 2" flexible PVC inside the system.
Thanks again for your help, and for the welcome.

No your valves Wouldn’t be underwater your run your pipe buried around the edges of the pond and can either create boxes with a lid to access valves similar to an irrigation system or DIY it with a rock/dead wood cover.

 

[ChrisK]

View attachment 155090@ChrisK
I think you would like to add Shubunkin goldfish as they are quite pretty and not destructive like koi. Your pond would be pretty small for many koi.

Shubunkin Goldfish, they come in many patterns

View attachment 155091

View attachment 155092

AGREED J. W.
That was my plan. I had some before, and they are exactly as you said.
I loved the Koi too. Especially the butterfly koi, but they uprooted every plant they could eat, and just made a general mess of the pond.

Thanks.

 

[combatwombat]

Thank you, Combatwombat.
This is very helpful but begs another question.
If I do use a single pump (I do have a backup pump-thanks) won't the ball valves be under water?
My intention was to use 2" flexible PVC inside the system.
Thanks again for your help, and for the welcome.

What @Jhn said. If you have a submersible pump and plan to run your plumbing inside the pond, you can just bring the pipe up close to water level where you want to place the valves. Maybe along the edge of a shelf behind an edging rock. Not a problem if they're a couple inches under water. You shouldn't be accessing them often.

 

[j.w]

AGREED J. W.
That was my plan. I had some before, and they are exactly as you said.
I loved the Koi too. Especially the butterfly koi, but they uprooted every plant they could eat, and just made a general mess of the pond.

Thanks.

Oh also have you seen the beautiful Shubunkins w/the very long tails too?

Love this white Comet one too!

So many choices out there!

 

[GBBUDD]

a LArger pond is recommended for koi full grown gold fish will take all the space in a 1600 gallon pond.

You mentioned the right pvc being flex pvc. do NOT buy the cheaper Kink free......

TWO PUMPS ARE ADVISABLE as not only to keep things running when one dies but its generally cheaper electric wise to have two smaller pumps push what one larger pump will but often it costs more for two pumps over one.

There are also koi that are cross breeds, like with the fancy gold fish to my knowledge they don't get that big probably equal to a adult gold fish. I have 4 of them ask me again in ten years. They are very cool like butterfly koi without the long body.

Are you planning a stream coming down the hill or are you thinking a one drop from the bog to the pond

 

[ChrisK]

Oh also have you seen the beautiful Shubunkins w/the very long tails too?

View attachment 155095

Love this white Comet one too!

View attachment 155096

So many choices out there!

Hi j.w.

Those guys are awesome. I've never seen any with the really long tails. I've always bought my fish locally. Are these special breeds that I can see online? If so, can you recommend a site? Thanks.

 

[ChrisK]

a LArger pond is recommended for koi full grown gold fish will take all the space in a 1600 gallon pond.

You mentioned the right pvc being flex pvc. do NOT buy the cheaper Kink free......

TWO PUMPS ARE ADVISABLE as not only to keep things running when one dies but its generally cheaper electric wise to have two smaller pumps push what one larger pump will but often it costs more for two pumps over one.

There are also koi that are cross breeds, like with the fancy gold fish to my knowledge they don't get that big probably equal to a adult gold fish. I have 4 of them ask me again in ten years. They are very cool like butterfly koi without the long body.

Are you planning a stream coming down the hill or are you thinking a one drop from the bog to the pond

Thanks, GBBUDD.
Yeah, I don't want the pond to be dominated by a couple of koi. So, goldfish/shubunkins is what I was thinking.
I like your idea of the 2 pumps. I was thinking of simplicity with only one pump, but the head height will require enough pressure, that it will probably be more controllable with pumps for each feature. Yes, I was planning a stream from the bog, and a more "direct" flow (a few drops) from the waterfall. Again, the 2-pump idea will give me more control of each.
I'm not familiar with the koi cross breeds. Is there an online site where I can see them?
I think I may have one of them from my old pond (I kept some of the fry when I moved). This one is much larger than the other fish and has a much larger body shape, and face. It's not that attractive, but he's thriving so I'll keep him.

Thanks again.

 

[addy1]

I have shubbies , some long tails, some not. They do great in our pond, leave the plants alone.

Easy to care for.

 

[ChrisK]

Thanks, Addy1.
That's exactly what I'm hoping for.

 

[Lisak1]

We have a bog at the top of a raised garden - about three feet above the pond. The bog itself feeds the waterfall, but we have a second feed (off the same line and pump) that creates more water flow. We have a series of ball valves that we can adjust to change the flow to one or the other. Once we got it dialed in, we pretty much leave it alone, but it is nice to know we could switch it up if we needed to at some point.

 

[ChrisK]

Thanks, Lisak1.
Great helpful info. My bog will be about 16+ feet above the pond with a steep grade in between.
I guess I'll be doing some math to determine pump size/flow. It's a shame, I have a few used/working pumps, but I don't think any of them will have the head height pressure that I need for the bog. However, they should work for the waterfall since they would be feeding it only. It's still a work in progress, and I'm in PA, so it's going to be time to stop the digging/construction soon. I'll have all winter to think this through. Thanks again.