Backyard Aquaponics
A place to discuss aquaponics

Sorry if this has already been discussed - I couldn't find any info though.

I have a 4000L per hour pump (will pump 1000L for 15 min of the hour - flood and drain). The piping has to go up 1m and along 3m. My question is, does anyone know the suitable diameter of the pipe?
I'm thinking 40mm should do it, but plumbing ain't my forte! (come to think of it, I'm not sure what is my forte ).

Cheers.

40mm is fine

Even 32mm, maybe 25mm would do the job, but go for 40mm, leaves room for more flow later on

It depends on the internal diameter of the outlet on your pump.

ie: If the outlet is 25mm, then there would be no benefit in using anything more than 25mm PVC pipe, in fact it would probably cause a reduction in pressure, depending on how you plumb the system up.

Mr Damage.

Bull Crap.

Sorry but your wrong.

Using a 25mm ID pump, does not mean that using 25mm ID pipe is more efficient.

A 25mm ID pump with 40mm ID plumbing will work a lot better, especially if there are a few elbows or T-pieces.

This has been discussed and tested previously.
Mr Damage, your post ignores the basic laws of plumbing.

Which are?

I am human after 3am, your human after 8am.


Just kidding.

A length of pipe that is 40mm ID with 40mm Fittings, has around 8 times the flow capacity of 25mm ID pipe with fittings (thanks Kuda).

A 25mm ID pump discharging into 25mm ID pipe is always working against the internal restriction of the pipe and the fittings.

A 25mm ID pump discharging into 40mm ID pipe is NOT working against the internal restriction of the pipe and fittings.

I work in hydraulics, try using a small (13mm) garden hose with 15 metre length from your tap and see how it goes, then try it with a larger (19mm) hose - the difference is huge.

Thanks guys, much appreciated. I had a feeling that 40mm was probably alright - more a case of 'best guess' than basic laws of plumbing. I was more worried about shortening the life of the pump than anything else (I think I heard that gem from somewhere - can't remember where though. Might have been a movie ).

Also, I can get my hands on some cheap 40mm PVC. K-ching!

Cheers OBO - that makes sense.

I lied... I'm very rarely human... but I had to put something in there!



That's not true!... It's still working against the internal restriction of the pipe, just not as much.

It all depends on whether you're chasing flow or pressure, you need to find a happy medium between the two. Depending on how he plumbs the system up, how many runs, how far, whether it's ring mained etc... a system with a 25mm ID pump outlet and 40mm pipe will run out of pressure before the same pump running 25mm pipe.

What would happen if he decided to use 50mm pipe instead of 40mm?... would he get more flow again?

Mr Damage.

Dude, seriously.

I once again refer you to the fact that I work in Hydraulics, and I know WTF I am talking about.


To make it simple for you:

If your theory was correct, they would have run 25mm pipe from Mundaring to Kalgoorlie. Instead of 300mm to 400mm pipework.

The pumps used to move the water from Perth to Kalgoorlie have around a 6 inch outlet. This discharges into a 12 to 15 inch pipe (depending on the age of the pipe). This ensures that the pumps are pushing into as little head pressure as possible.

A ten metre run of 40mm pipe (from a 25mm pump) would have a very similar flow rate to a 50mm pipe of the same length. However a 25mm pipe would have a lot less flow.

Once again, if you dont believe me, try it yourself.

Yep, I saw that the first time you mentioned it!



That's because they were looking for flow, not pressure!



Similar flow, but less... correct?... what about if he went to 65mm, or 80mm pipe?... by your reckoning it wouldn't make any difference.

and yes, the 25mm pipe would have less flow if you are talking about an open ended, or relatively unrestricted outlet at the end, but if your talking about a ring mained reticulation system, like those Joel puts around the top of his grow beds, the 25mm would deliver better pressure at probably similar flow.

I have no doubt you know a lot about hydraulics, but high pressure hydraulics and water reticulation systems are two different kettles of fish.



I spent many years designing and installing reticulation systems, and I never installed one that didn't work exactly as it was supposed to! I've installed reticulation systems to entire sports complexes, designed by engineers, I've never seen one that goes from a 150mm pump outlet for example, and jumps up to a 250mm pipe.

In hydraulics it's different, a 1/2 inch hydraulic line can feed a 50mm ram, because you're dealing with very high pressure.

I don't quite get your point about the 13mm v's 19mm garden hose... yes there would be a difference, the 19mm may have more flow but much less distance and pressure, the 13mm would have much more pressure and distance.

It's like I said, you need to find a happy medium between the two, and it depends on how the system is plumbed up!

But all this chest beating is irrelevant, he's sorted his plumbing problem out by the sounds of it!

Mr Damage.

Basic Law Of Aquaponic Plumbing: The first pipe coming from the pump shall be One Size Larger diameter than the pump's outlet size.

I have been using this as a basic law anyway, is there actually a consensus on this?

Rick

It's called friction loss Mr Damage.

at that flow rate, you get about 43" of head loss per 100' of piping in 3/4" ID piping
Using 1" ID piping you get 13",
Using 1 1/4" you get 3.5"...

As you can see, bigger diameter = less friction loss= more flow at the end of your run.

Obo you are right in all you say Mr Damage you are wrong sorry how do i know for years i was trouble shooter for a large valve making company and some of the things engineers tried to do just defies all logic

Dipping my toe into unfamiliar waters, what about the recommended pipe size as stated by the manufacturer?

I run my laguna 16000 on a 40mm to 25mm

When I had my laguna 3000 I ran it on 25mm

These were the manufacturer recommendations.

I would like to read the full instruction sheet