Help with pipe size, gravity and pumps


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Hi All

I'm building my first major pond and I need help with pipe size and logic. The pond will have skimmer that feds into a bog and a bottom drain that feeds into bog via a settlement tank.

schematic.png

So I really want to confirm what will be the best pipe size to use. For the Bottom drain I was going to use a 4" pipe into the the settlement tank and thinking out 2" for the rest. I'm in the UK so will use rigid PVC with solvent weld joints,

My concern is the settlement tank and pump to bog; is it possible the pump could be to fast for the gravity fed settlement tank, the settlement tank will be open so I'm worried the pump will suck to fast and start emptying the tank because the gravity fee can't keep up?

I'll appreciate any help or advice
 
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Mmathis

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Oh my, that is too complicated for me, so sorry, I can’t advise about pipe sizes. Most of us just plumb the pond directly to the bog.
 
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Oh my, that is too complicated for me, so sorry, I can’t advise about pipe sizes. Most of us just plumb the pond directly to the bog.
I wanted a bottom drain as the main pond was quite contemporary, I was advised to use a settlement tank between it and the bog. The other half is a skimmer feeding the bog.
 
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I wanted a bottom drain as the main pond was quite contemporary, I was advised to use a settlement tank between it and the bog. The other half is a skimmer feeding the bog.

You definitely want a way to filter debris from a bottom drain before sending to bog, whether that's a settlement tank, sieve, or something else. I'm struggling to remember the "rules of thumb" for pumping from a gravity fed tank, but the folks over at koiphen geek out about that stuff.

What's important about a settling chamber, as you suggested, is that crud actually settles in it, which means you need as much dwell time as possible. Probably at least a few minutes.

5,000 gph = 83 gpm. 83 gpm flowing through a 260 gal tank would give you a 3 min dwell time. That's probably right on the edge of "pump too big" or "chamber too small."

Realistically, you won't flow 5,000 gph after accounting for head loss, so you might actually be okay. If you know your elevation change between pump and bog, how far and what fittings are needed to deliver water to the bog, and the pump you intend to use, we can calculate your dynamic head and get a more realistic picture of how the system will actually function.
 
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You definitely want a way to filter debris from a bottom drain before sending to bog, whether that's a settlement tank, sieve, or something else. I'm struggling to remember the "rules of thumb" for pumping from a gravity fed tank, but the folks over at koiphen geek out about that stuff.

What's important about a settling chamber, as you suggested, is that crud actually settles in it, which means you need as much dwell time as possible. Probably at least a few minutes.

5,000 gph = 83 gpm. 83 gpm flowing through a 260 gal tank would give you a 3 min dwell time. That's probably right on the edge of "pump too big" or "chamber too small."

Realistically, you won't flow 5,000 gph after accounting for head loss, so you might actually be okay. If you know your elevation change between pump and bog, how far and what fittings are needed to deliver water to the bog, and the pump you intend to use, we can calculate your dynamic head and get a more realistic picture of how the system will actually function.
Thanks for the reply.

I can take a look over on koiphen, I need to make sure they don't try to convert away from a bog filter :)

I can make the settlement tank a bit bigger, but don't really want it too big or too costly, I could slow the flow into the bog, are their any other low maintenance options?

The 5000gph was just a estimate base on a bit of research, I think I need a total of 8250 gph going into the bog from the two pumps, so I could perhaps run it at 4000gph.

The water level in the bog will only be a little higher then the pond around 150mm 6"

Please do not assume I know what I'm talking about :unsure::D , I'm just trying to use the expertise on this site to help me not make an expensive mistake.

Thanks
 

Mmathis

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@GaryMoz I haven’t logged into KOIPHEN lately, but in general, the trend toward bogs is becoming more popular. Even if they do try to sway you, just ignore that part of the conversation.
 
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8,000 gph is a lot of flow to a bog you gave us depth but not the size of it . I run a similar idea but i do not through 8000 to the bog more like 4 to 5000 gph and i built a second peastone bog that gets like 3,000 gph. my bog is 20'x8'x6' but i am running a snorkel , centipede, matrix blocks, and 30" of assorted layers of gravel.

The settling chamber will need to be at the same elevation as is the pond or slightly higher.

But in stead of a settling chamber I'd look into a sieve filter . this can work as gravity feed but you have to work it out so if the power goes out the sieve will stop working and not drain out the pond. My plan is to incorporate one to my pond but it will be fed by the pump and gravity back to the pond. so if the power goes out it goes down. In order for a settling chamber to work it needs a good volume for the water to just sit and no current just displacement.
 
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8,000 gph is a lot of flow to a bog you gave us depth but not the size of it . I run a similar idea but i do not through 8000 to the bog more like 4 to 5000 gph and i built a second peastone bog that gets like 3,000 gph. my bog is 20'x8'x6' but i am running a snorkel , centipede, matrix blocks, and 30" of assorted layers of gravel.
Thanks for the reply'

I estimated the rate based of info from a site ozponds, There is a very good chance I missed read it, I will go and check it, but he suggested water should take 10 -15 mins to pass through the bog, what I may done is used the total volume of bog and not volume of water in bog, if I did that would bring it down to 5000gph but that will be somewhat faster then yours, more research required.:)

My bog will be a very very similar construction but a bit smaller, it will be around 20' x 4' x 5'.

Do you have any comments of pipe sizes to use?

Thanks
 
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Haha. Koiphen has come back around to the bog filter a bit. Or at least they aren’t as hostile towards it.

I see @GBBUDD mentioned flow rate through the bog, which is important. If you’ve calculated 10-15 min dwell time, then you should be covered there. But if you calculated based on total volume of bog—not volume of water in bog—then you need to recalculate because a bog is only about 30-40% water, so your dwell time will be less than half what it would be if the gravel weren’t there.
 
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I been reworking my calcs and seen where the issue is.

The pond is 26000lts so normally would look at trying to recycle the amount per hour, so 26000lph (7000 gals)

The bog filter has a total volume of 7000 ltr (including gravel\crates etc) so I think it will need around 17000lph (4500gph)

schematic v2.png

So I will need to either divert the excess water so it does not go all the way through the bog filter or reduce the pump rate, so ponds takes longer cycle i.e. 7000/4500 around 1.5 hrs, which would be better?

Also what are the best pipe sizes to use?
 
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3" minimum and i would also install a vacuum breaker and or a pin hole to break the syphon when the power goes out /
PVC Pipe sizes are different than the size the pipe is called. For example, a 1 inch PVC Pipe is actually 1.315 inches in outside diameter, and 1.029 inches in inside diameter. Fittings follow this same pattern, a 1" fitting has a 1.315 inch opening to accept a 1 inch pipe, which actually measures 1.315 inches in diameter. The opening in the fitting and the size of the pipe are exactly the same size; this is called an "interference fit" and the two parts are intended to be "welded" together using PVC glue, which is really a solvent that melts the two parts together.
 
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3 inch to feed the bog will be over kill but it will alow for growth if you need it. You can split the line and tap with a 2 inch and have that dump at the top of the bog by the waterfall for a more dramatic look or have that water used to circulate the pond , insuring there's no dead spots.
2 inch is what I use for individual features like a skimmer if there is also a main drain . That would always get a 3 or 4 inch better to have and not need then need and not have.
2 inch for return jets for circulation
And all pipe is schedule 40 pvc or FLEX pvc ..........NEVER USE KINK FREE...
 
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3" minimum and i would also install a vacuum breaker and or a pin hole to break the syphon when the power goes out /
PVC Pipe sizes are different than the size the pipe is called. For example, a 1 inch PVC Pipe is actually 1.315 inches in outside diameter, and 1.029 inches in inside diameter. Fittings follow this same pattern, a 1" fitting has a 1.315 inch opening to accept a 1 inch pipe, which actually measures 1.315 inches in diameter. The opening in the fitting and the size of the pipe are exactly the same size; this is called an "interference fit" and the two parts are intended to be "welded" together using PVC glue, which is really a solvent that melts the two parts together.
Thanks for the reply.

I will look at using 3" or the metric equivalent

I was going to include a breather tube in the bog which is designed to stop the syphon. I will take a look a vacuum breaker
 
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Thanks for the reply.

I will look at using 3" or the metric equivalent

I was going to include a breather tube in the bog which is designed to stop the syphon. I will take a look a vacuum breaker
There are $15 dollar vacuum breakers you can find at any good hardware store . And then there are $300 or more the 15 Is all you need.
I mentioned before make sure your settlement filter is at the same plain as is the pond . To get the balance right of pump to gravity is not easy and always risky. When all three are equal heights then the pump does the job making everything work and when power goes out everything levels out
 
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3 inch to feed the bog will be over kill but it will alow for growth if you need it. You can split the line and tap with a 2 inch and have that dump at the top of the bog by the waterfall for a more dramatic look or have that water used to circulate the pond , insuring there's no dead spots.
2 inch is what I use for individual features like a skimmer if there is also a main drain . That would always get a 3 or 4 inch better to have and not need then need and not have.
2 inch for return jets for circulation
And all pipe is schedule 40 pvc or FLEX pvc ..........NEVER USE KINK FREE...
So keep rate up to what pond requires and divert the excess for jets or water fall.

I'm trying to find the equivalent of schedule 40 pvc in the UK, our waste pvc is has thinner walls. A lot of pipe will be buried, so I rather be safe than sorry, I seems irrigation companies sell better quality pipe at reasonable prices.
 
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If you plumb your pumps separately, then dual 2" pipes to the bog are more than sufficient. If you're combining them ahead of the bog, then definitely 3".

Like @GBBUDD said, you can use valves to experiment and dial in exactly how much flow goes to the bottom of the bog. Divert/ dump the rest out on top or send it somewhere else like circulation jets, another waterfall, another filter, etc.
 
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So keep rate up to what pond requires and divert the excess for jets or water fall.

I'm trying to find the equivalent of schedule 40 pvc in the UK, our waste pvc is has thinner walls. A lot of pipe will be buried, so I rather be safe than sorry, I seems irrigation companies sell better quality pipe at reasonable prices.

Irrigation pipe might work, but imagine it will be hard to source in the size you need. Around here, a 2" pressure rated pipe would only be used on extremely large residences or commercial/industrial applications.

What's the wall thickness of your waste pipe? Over here, pressure pvc and waste pvc are the same wall thickness but their manufacturing process gives them different pressure ratings. Waste pipe is the standard over here as it's cold water only and pressure is very low in a pond system. You might be fine using waste pipe, but we'd need to know more about it.
 
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There are $15 dollar vacuum breakers you can find at any good hardware store . And then there are $300 or more the 15 Is all you need.
I mentioned before make sure your settlement filter is at the same plain as is the pond . To get the balance right of pump to gravity is not easy and always risky. When all three are equal heights then the pump does the job making everything work and when power goes out everything levels out
The pond and settlement tank will have the same depth and top levels, the filter will be about 6" higher, so It should be okay
 
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2 two inch lines can not carry what one 3 inch can . From a pump that pushes 4000 gph then yes a three inch is over kill but even so once it meat the bog and goes underground there I would go hands down 3 inch as I already made that error last time around . Even though I never plan to use the full 3 inch with a flow of 12000 gph ovr the bogs waterfall .when company comes over I may through 8 or 10000 gph at it for effect.
 
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That's where I have to disagree. . Waste pipe is or can be so cheap one wrong move and it's a goner.
scedule 40 is considerd waste pipe but is the go to for millionsof swimming pools. However there is also drain lines for camper rv's and that drain line I would not touch with a ten foot pole. If I'm placing tens of thousands of pounds or earth or boulders over a pipe it's going to give me a bit of insurance that it can do much more then I need it too. Not a place I want to revisit when everything is built.
 

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