The one where CW and GBBUDD argue about pipe sizing.

[Jhn]

I’ve heard the same, but but plumbers are typically talking about household plumbing fed by municipal, relatively unchanging water pressure. It makes more sense in that application. As far as I can tell, that’s still wrong, but closer to reality in household plumbing.

You can easily test that by timing a 5 gallon bucket fill from a hose and then doing so again after turning the nut in your pressure reducing valve. It fills faster/slower based on the pressure you set.

You’re right that in a lot cases we’re splitting hairs, but in a lot of other cases we’re talking about giving out phenomenally bad advice that either wastes lots of money or doesn’t deliver the desired flow.

Let’s go back to that 11k GPH pump from Sequence (and many others) with a 1.5” outlet.

If we believe that the smallest fitting in a plumbing system sets the maximum flow rate, then we have to believe that this 11,000 GPH pump can only deliver 3,600 GPH of flow, wide open with no hose attached.

Do you believe that to be true? That’s the basis that this argument is built on.

My understanding of it is as gbbudd described it in the other thread, but once again really not my area.

As for wasting lots of money on bad advice, imo the Safest way to not waste money is not get in the pond hobby. Yes, people can get bad advice and waste tons of money, but just like anything do your own due diligence, use common sense and that can be avoided, but I digress, since this isn’t really what this thread is about.

 

[GBBUDD]

we

I would say it is better for future upgradeability. If I want to up my flow in two years I need larger pipes to handle that flow, and it would be easier to install them at the time of initial construction.

Wise words young man that would be the only time I would increase size PLANNING FOR THE FUTURE. look at that a 14 year old came up with the wisest words and kicked the topic to the curb
Thank you...

 

[combatwombat]

If I'm wrong, then I need someone to explain how an 11,000 gph pump with a 1.5" outlet can deliver more than 3,600 gph. That one's a real head scratcher...

 

[GBBUDD]

Safest way to not waste money is not get in the pond hobby.

And there is a very close runner up.


As I am dumping oh over 6 k now on a filter alone

 

[combatwombat]

I’m glad you’ve come to your senses! That was a close one.

 

[netvine]

I just came across this thread staring at my 1.5”in x1.5”out leaf trap and my 2” piping and fittings elsewhere. I got it using similar logic, the sequence pumps i was looking at had 1.5” outlets and the 2” would have less friction overall in the system. (So the low power periha would be fine with 1.5” primer pot was my thinking) Even with a head calc wizard im still unsure of how much head loss from 2” bulkhead reduced to 1.5” through leaf trap back to 2” pump. Is there some sort of way Through positive affirmation or stretching and breathing anyone has found that works to stop overthinking this stuff?

 

[combatwombat]

@netvine: I’ve never seen a friction loss chart that included bulkheads or leaf strainers, but you can safely assume they do add some head pressure.

For most other fittings, you can look at a chart like this to find the equivalent length of straight pipe that a certain fitting of that size will add to your system.

So, as you’re adding up all the lengths of pipe you have, you can look at that chart to find The equivalent length of pipe added by your fittings and just add that to your lengths of straight pipe.

And you’re absolutely right that upsizing to 2” pipe reduces head over 1.5” regardless what else is in your plumbing system.

Even if a 1.5” fitting reduces your total possible flow to 3,600 GPH, you still benefit from 2” plumbing because 2” at 3,600 GPH will add 5.8’ of head for every 100’ of pipe and 1.5” at the same flow will add 20’ of head.

So, assuming you want less dynamic head, you will always benefit from using larger pipe, even with other restrictions in the system.

 

[GBBUDD]

If I'm wrong, then I need someone to explain how an 11,000 gph pump with a 1.5" outlet can deliver more than 3,600 gph. That one's a real .

For those looking for the facts on simple pond plumbing. And what size pipe you'll need with your pumps. Regardless of feelings here is a chart of what the most common sized pipes with gravity feeds, simple psi pressures, and with the pressures turned up a bit.

This table shows the maximum flow rates for them. I extremely doubt though, I am not a Hydro dynamics engineer as I have said before. Can you ever get a 1 1/2 pipe at 7000gph to supply the amount of 25,000 gallon to a 3 inch pipe in the same time frame under any circumstances. Now as @TheFishGuy said one practical reason to have a pump with a 1 1/2 outlet be increased to a 3 inch is for growth. Where the pipes will be buried ounder the pond . Rocks etc now that gives you expansion. If you do replace your pump and add on to the pond down the road. The only time that might be a problem is with a tall waterfall for example 15 feet the extra weight of the larger volume of water will work against you and lesson the flow.

 

[bagsmom]

First, let me begin by saying numbers just jumble around in my brain and they sound like the teacher on Peanuts/Charlie Brown. Mwah mwah mwah. There is a lot of math-y discussion happening.
My brain perked up at this conversation, though, because it could be relevant to my bog construction. My pump vault has a 2" outlet. My flex PVC pipe is 2".
I had thought about using a 3" pipe - or even 4" for the bog/wetland filter pipe (where the water will come out through a bunch of slits cut in it.) I thought the larger pipe would make it easier to cut enough slits without accidentally cutting through the pipe.
Are you saying upsizing this pipe is a mistake? And that I need to stick with 2"?
Thanks!

 

[combatwombat]

First, let me begin by saying numbers just jumble around in my brain and they sound like the teacher on Peanuts/Charlie Brown. Mwah mwah mwah. There is a lot of math-y discussion happening.
My brain perked up at this conversation, though, because it could be relevant to my bog construction. My pump vault has a 2" outlet. My flex PVC pipe is 2".
I had thought about using a 3" pipe - or even 4" for the bog/wetland filter pipe (where the water will come out through a bunch of slits cut in it.) I thought the larger pipe would make it easier to cut enough slits without accidentally cutting through the pipe.
Are you saying upsizing this pipe is a mistake? And that I need to stick with 2"?
Thanks!

The bigger the pipe, the slower the flow will be inside the pipe, which is a good thing in a big (and most other plumbing in a pond). There’s no mistake using a larger pipe for distribution in your bog.

How are you cutting your slits? You can set the depth on a circular saw or make a stop block for a miter saw to prevent from cutting too deep.

 

[bagsmom]

The bigger the pipe, the slower the flow will be inside the pipe, which is a good thing in a big (and most other plumbing in a pond). There’s no mistake using a larger pipe for distribution in your bog.

How are you cutting your slits? You can set the depth on a circular saw or make a stop block for a miter saw to prevent from cutting too deep.

Great! Thank you! The hubby will do the sawing. I think he will use the "chop saw" or the table saw.

 

[GBBUDD]

The question is how deep is your bog going to be ? I WOULD WANT BONE DEAD MINIMUM OF 12 " OVER THE PIPE the roots can get down to the slits and start to clog them.
i'm heading for 24 " in my new bog over the matrix blocks

 

[bagsmom]

The question is how deep is your bog going to be ? I WOULD WANT BONE DEAD MINIMUM OF 12 " OVER THE PIPE the roots can get down to the slits and start to clog them.
i'm heading for 24 " in my new bog over the matrix blocks

I think it is right about at 24". It has kind of a bowl shape for stability. It might be 30" at the deepest point in the center but the bulk of it will be about 24".

 

[GBBUDD]

I just filled my bog. 12" of snorkel and larger rock 4 to 6 then the aquablocks. 2-3 inch rock on top of that for 6 inches then 18 inches of 3/4 with 4 inches of 3/8" i should have enough surface area for 10 ponds

 

[Bluerooster]

If I'm wrong, then I need someone to explain how an 11,000 gph pump with a 1.5" outlet can deliver more than 3,600 gph. That one's a real head scratcher...

According to the charts you must have at least a 4" pipe to flow 11000 gph @ ~5ft/s. But if we increase the flow velocity to 34 ft/s it will happily move 11000 gph through a 1.5" pipe. It's all relative: flow rate- flow velocity- pipe size- head - and pressure. All those must be taken into account.