# pipe diameter, flow rate and velocity



## Andrew Butler (31 Aug 2018)

In need of someone who understands these things better than me.
I'm looking to see what size pipe is needed for a filter to operate without being restricted so in other words how big the diameter of a pipe needs to be to allow a particular amount of litres per hour.
Am I correct to think I need to know the velocity of the water to calculate this?
Hopefully someone out there understands these things and can give me some guidance.
I have used the calculator below but I think I need the velocity to get the correct answer.
http://www.pipeflowcalculations.net/pipediameter.xhtml

This is all to do with spraybar calculations; the general rule I was given was to match total area of holes in the spraybar to the diameter of the pipe BUT both the Fluval G3 and G6 have the same size pipes yet very different flow rates: 700 and 1000 litres per hour.
So this would mean if I followed the rule then my spraybar would have the same overall area of holes for both filters which I don't think is right and the overall area of holes I calculated is very different to the sprayar Fluval supply which is the same with both filters although it can restrict flow on the G6.

I look forward to someone with understanding to educate me and hopefully help me fill in the blanks.

Cheers
Andrew


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## Zeus. (31 Aug 2018)

Hi M8 

I use http://www.1728.org/flowrate.htm to get my flow rates when going from a 25mm pipe to many small holes in a spray bar. Using the cross sectional area of the 25mm and comparing to total cross sectional area of the holes in the spray bar doesnt work due to the 'Hagen–Poiseuille law' 

I calculated the velocity from the pipe diameter and the pump/filter flow rate and say I got

a 28mm pipe and 3000l/h flow rate from pump/filter gives  135cm per sec Velocity

then I decide on the spraybar diameter holes say 4mm and use the 135cm per sec Velocity which yields 61 litres per hour

so to keep the same 3000l/h its 3000 /61 = 49 so 49 holes of 4mm diameter to yield 'about' the same flow rate

But if holes 5mm yeilds 95 l/h so 3000/95 = 31 holes.

well thats the method I used


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## Andrew Butler (31 Aug 2018)

What I'm trying to do is take the flow rate and see how big the pipe would need to be for it to allow that amount of water free passage but no more; does that make sense?
As I said both the Fluval G3 and G6 have the same size hose but different flow rates so surely the one with less flow doesn't actually require the pipe to be that big to let that amount of water past?



Zeus. said:


> 'Hagen–Poiseuille law'


Hi Karl, First time I've ever heard of that one 

I just run how my maths compared to the results using the above and the results aren't far off but I take that on board for the future.
area of 28mm pipe = 615.75
area of 4mm pipe = 12.57 (615.75/12.57=48.98568) Hagen–Poiseuille law =  49.18033
area of 5mm pipe = 19.63 (615.75/19.63=31.3678) Hagen–Poiseuille law = 31.57895


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## Zeus. (31 Aug 2018)

Andrew Butler said:


> Fluval G3 and G6 have the same size hose but different flow rates so surely the one with less flow doesn't actually require the pipe to be that big to let that amount of water past?



Yes/No/maybe- all depends on why they used the same size pipe. The one with the lower flow rate with a smaller pipe may take a big hit due to the resistance in the pipe and it may need that size pipe to maintain that flow rate. So its pump dependant also, plus I always find out what the smallest diameter is within the pump/filter assembly and that will be the point of maximum resistance and than make sure all piping is bigger than that and swept bends where possible or extra diameter bends.


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## Andrew Butler (31 Aug 2018)

It's to calculate the area of holes needed in the spraybars for each one; they can't both be the same surely? If you want to get 7000 LPH through a hole you wouldn't physically need the same size you would to get 10000 LPH through would you?
I'm leaving the pipe the same size just want to be able to calculate the area of holes needed to match the flow. How do I find out the velocity by only knowing the flow rate?


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## foxfish (31 Aug 2018)

You could just try out different hole sizes and spacing useing sacrificial pipe.
You might find your local B&Q sells 20mm black pipe used by electricians or my favourite.. 21mm overflow pipe.
Armed with some pvc tape, battery drill and a few drill bits around 3-6mm, you could experiment and find the best format for your individual pump power.
I think that maybe the efficiency of the pump, it’s wattege and impella design would make equations differcult?


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## Andrew Butler (31 Aug 2018)

I've got some sacrificial pipe if I need it but I thought it would be possible to determine how big a pipe would need to be and fit X amount of water through per hour.


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## Zeus. (31 Aug 2018)

Andrew Butler said:


> If you want to get 7000 LPH through a hole you wouldn't physically need the same size you would to get 10000 LPH through would you?



No depends on the head of pressure the pump can generate, higher the head of water the pump can generate the higher the pressure, higher the flow rate, plus higher the flow rate the more kinetic *energy* the water has to create FLOW/turnover in the tank



Andrew Butler said:


> How do I find out the velocity by only knowing the flow rate?



http://www.1728.org/flowrate.htm you also know the diameter of the pipe so just enter the flow and you get the velocity.

The calculations just give an idea of the flow OFC then its trail and error, why do you need to know the flow anyway ? Think it because you thinking of the x10 guideline for output, if it is this is a guide to help you get enough tank turnover/flow in the tank. If your filter gave an output of a litre an hour but your powerhead was creating lots of flow in the tank the output of the filter/spraybar is irrelevant, as long as theirs enough filtration. So many holes in a spraybar of small diameter create many 'jets' with high energy water which push a higher volume of water around but also reduces the filters output. But a few big holes or many big holes push little water about the tank as the water has less energy but there will be a higher. So filter output isnt everthing.

As our Clive says 'FLOW' is king, not filter output, filter output x10 is an estimate of manufacturers stated outputs that you are advised to match the tanks size, But the trick is getting a good turnover by the use of well placed spraybars lily pipes etc



foxfish said:


> You could just try out different hole sizes and spacing useing sacrificial pipe.



, I did the maths then just used smaller holes and checked the tank flow, then increased the holes 0.5mm and a few more to try and generate a Gyre in my tank, one spray bar has never been changed as its fine the other I have modded here and there and have a spare also with differant size holes, using one ATM with tape over some holes


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## Andrew Butler (1 Sep 2018)

Zeus. said:


> The calculations just give an idea of the flow OFC then its trail and error


So what you're saying is ignore most of the things I have read about calculating spraybar holes and spacings? - Namely match overall area of holes in spraybar to filter pipe area.

So if we look at the 2 filters I'm talking about; Fluval G3 and G6
Fluval G3 - 700lph flow rate - 1285lph pump performance - head height 180cm
Fluval G6 - 1000lph flow rate - 2460lph pump performance- head height 210cm
Both of these use 16mm internal diameter pipe.

There are so many conflicting things online about spraybars but the above calculation seemed one that most people suggested, including the experienced ones.
It seems pointless doing the maths if after that it's just trial and error.
How will you ever truly know that your filter is pushing the correct amount of water through? Even if you set it up and time how long it takes it to fill a bucket that doesn't account for the resistance the water would normally give your filter in the aquarium.


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## soggybongo (1 Sep 2018)

i get what you are saying Andrew as water can only flow at a certain maximum rate through a hole before it cannot flow any faster. it will be a trial and error exercise the main problem will be excess back pressure and pump premiture failure if it is worked too hard.


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## Andrew Butler (1 Sep 2018)

soggybongo said:


> i get what you are saying Andrew as water can only flow at a certain maximum rate through a hole before it cannot flow any faster. it will be a trial and error exercise the main problem will be excess back pressure and pump premiture failure if it is worked too hard.


I also get what is meant about velocity and that being a big factor.
If 100 people run in* single file* then they will get past a point faster than 100 people walk past it - unsure if this is a good analogy or not!


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## Andrew Butler (1 Sep 2018)

Fluval actually send a spraybar with the G3 and G6 but it is the same one for both.
I have used it before BUT not only is it a bit fiddly and not fit my tanks but I found it to restrict flow once the slightest bit of detritus had built up.
I thought I would have a look at it and see how many holes and what size they were:
There are 14 x 3mm holes on each spraybar which equates to an area of 98.96.
The 16mm pipe has an area of 201.06 so the supplied spraybar doesn't even cover half the area of the 16mm pipe BUT remember it only takes the slightest bit of build up to restrict the flow.


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## Zeus. (1 Sep 2018)

Andrew Butler said:


> The 16mm pipe has an area of 201.06 so the supplied spraybar doesn't even cover half the area of the 16mm pipe BUT remember it only takes the slightest bit of build up to restrict the flow.



Smaller holes restricts the output of the filter but the water is coming out with more energy which can result in better tank turnover with good placement 'trail and error', and 'Tank turnover is the FLOW which is King' in Clives posts


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## Andrew Butler (1 Sep 2018)

So to surmise:
The only way to work out the number of holes needed in a spraybar is 'trial and error' - Curse all those people that published that formula and made me think it was the way to go!



Zeus. said:


> Smaller holes restricts the output of the filter


Just remember this does damage the pump in your filter over time.


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## Zeus. (1 Sep 2018)

Andrew Butler said:


> The only way to work out the number of holes needed in a spraybar is 'trial and error'



No, the calculations get you close to the number and size of holes required, just start off with smaller holes IMO and check tank turnover



Andrew Butler said:


> Just remember this does damage the pump in your filter over time



So does putting filter media in the filter as it increases the load on the pump, esp if its crammed with fine media, doubled the life of my pump by getting a spare pump and swapping it over when it needs a good clean


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## Tom Raffield (1 Sep 2018)

Hi everyone,

I'm going to jump in here as I am in the middle of my spray bar adventure! I have constructed a spray bar for my FX4 with the excellent guidance of Andrew which uses the theory of matching pipe size to the number of holes. This led to the current 1m spray bar that is sitting in my Juwel Vision 260.

Whilst doing my water change this morning I thought I would play around with the bar a little as I believe the pressure isn't sufficient for the size of the tank (this might also be contributing to my CO2 issues). This first video is the bar with no tweaks and therefore at my 'normal' flow and pressure:



Then I decided to start blocking holes. I didn't do any calculations as to which ones to block. I just started in the middle and tried to miss an equal number each time. This is the bar with 10 holes blocked.



And then I built up to this which is 17 holes blocked.



From what I have read and seen, an ideal pressure would get the water to hit the front glass. Whilst there is a clear progression from the first video to the last, do you think that I have reached an adequate pressure to help the flow and distribution in the tank? On the flip side by covering 17 of the 40 holes, is this likely to lead to issues with the filter/pump. I have 2 more sections of piping and will be producing a new bar when I know what to do with it. 

Other than playing around with the hole configuration, is there anything else that could be done? The hosing pipe that leads to the bar is quite long. I made it this way when installing the FX4 so I knew I had enough hose - would reducing this help? Would removing some of the media from the FX4 be beneficial? I have more in there than it came with as I still have media from my Juwel internal in there when I was trying to start the FX4 up.

As always, any ideas and suggestions welcome!


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## Andrew Butler (1 Sep 2018)

Hi Tom,
As you know it was me that told you to match total area of holes in spraybar to pump hose so I take the blame for that here.


Zeus. said:


> the calculations get you close to the number and size of holes required


In this case Karl you can see it is nothing like close!


Tom Raffield said:


> do you think that I have reached an adequate pressure to help the flow and distribution in the tank?


In my opinion the spraybar still looks down on power, I would be tempted to angle it up just a little - not saying that will solve this but I would have my spraybar angled slightly upwards anyway.
I would be tempted to try covering a few more holes too and see what it's like then.


Tom Raffield said:


> is this likely to lead to issues with the filter/pump


I can't answer that but you could try and see if you can map the flow rate of your filter with/without the spraybar - the FX4 is meant to have a flow rate of 1700 LPH


Tom Raffield said:


> Would removing some of the media from the FX4 be beneficial?


If you check out Karls posts I'm sure he has a picture of the media he runs in his FX6 which might give you an idea.

I think this is going to be a bit trial and error unless someone else can tell you better.


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## Andrew Butler (1 Sep 2018)

https://www.ukaps.org/forum/threads/olympus-is-calling.43046/page-9#post-533072

Karls FX6 media


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## Tom Raffield (1 Sep 2018)

Andrew Butler said:


> https://www.ukaps.org/forum/threads/olympus-is-calling.43046/page-9#post-533072
> 
> Karls FX6 media



I use the same amount of sponge but in the centre red baskets have fully packed the media which came with the FX4 (this fills the baskets) and on top of that I have bags of cerax from the Juwel. Perhaps I have gone a little OTT!

As a side note @Zeus. that tank is fantastic - what an focal point for the room. Looking at mine I should be covering it in a black sheet and pretending its not there. Maybe I could just stick a picture of yours on the front and pretend!


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## Andrew Butler (1 Sep 2018)

Tom Raffield said:


> I use the same amount of sponge but in the centre red baskets have fully packed the media which came with the FX4 (this fills the baskets) and on top of that I have bags of cerax from the Juwel. Perhaps I have gone a little OTT!


why not try emptying all the baskets and just see what impact that has on the spraybar before you block anymore holes up?


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## Zeus. (1 Sep 2018)

Tom Raffield said:


> and on top of that I have bags of cerax from the Juwel



Sounds like a right output killer 



Andrew Butler said:


> why not try emptying all the baskets and just see what impact that has on the spraybar before you block anymore holes up?



Good idea then you can see how much the media is impacting the output


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## Zeus. (1 Sep 2018)

An early pic of one spray bar config I used





Still use the same one on the right just added a couple of holes on the bends so the water hits the side of glass.


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## foxfish (1 Sep 2018)

Water flow It a fascinating subject, I don’t pretend to know any calculations but I seem to have made dozens of spraybars that work really well!
They might not produce the ultimate performance but I don’t really care, as long as it looks pretty good to my eye that is fine with me.
I think that a non compressible substance like water is easily effected but the smallest defect in it path.
 Every bend or angle will slow it down, the distance and the height will effect the flow.

Take a bore hole pump, it can pump water from 300’ below ground at a main pressure rating in only a 32mm pipe at 2000lph. A high power pump like that will deal with restrictions far better than a 25w fishtank filter.

In my case I have always just guessed a starting point, maybe one 4mm hole every 150mm.
I test it with a lowered water level and I do indeed aim for the jets to reach the opposite glass, I just drill more holes until I get a drop back in the jets force. Then I might try another test useing 5mm holes... etc....
That might seem a round about way to some folk but I love playing with water, pumps and pipe work, all part of the fun for me....
Just using a poorly drilled hole will have some effect, a burr on the inside of the pipe or a slight angle will both show up in the individual  jets.
Certainly getting a nice smooth flow path from the filter to the spray bar will help retain the max the pump can offer.


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## john dory (1 Sep 2018)

Don't know if it's any help,but my fluval spraybar is 800mm long,and has 20 holes.
This allows the jets of water to hit the front glass about 5 inches below the height of the the spraybar.
Tank is 15 inches wide.
My filter is a fluval 406(1450lph)with the baskets half full of noodles.


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## Andrew Butler (1 Sep 2018)

john dory said:


> Don't know if it's any help,but my fluval spraybar is 800mm long,and has 20 holes.
> This allows the jets of water to hit the front glass about 5 inches below the height of the the spraybar.
> Tank is 15 inches wide.
> My filter is a fluval 406(1450lph)with the baskets half full of noodles.


Hi John,
it may have 20 holes but how big is a hole?!


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## Andrew Butler (1 Sep 2018)

foxfish said:


> Water flow It a fascinating subject


I just thought there would be a  simple enough formula given I know the filter circulation from my pump and not just the pump output that many filters give.
Trial and error seems your approach like many others and I'm not knocking it but how do you know when you are putting back pressure on your filter?

@Zeus.
interesting reply
https://barrreport.com/threads/pipe-diameter-flow-rate-and-velocity.15953/#post-154699


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## john dory (1 Sep 2018)

It's actually 2 fluval spraybars stuck together..so I reckon 3 or 4 mil.


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## Andrew Butler (1 Sep 2018)

john dory said:


> It's actually 2 fluval spraybars stuck together..so I reckon 3 or 4 mil.


Hi John
There's a big difference in total area between the 2 sizes.
if you have 20 x 3mm holes that's 141.37 and 20 x 4mm holes 251.32
That's nearly 1.8 times the amount believe it or not!


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## john dory (1 Sep 2018)

Sorry,for the confusion,my reply was aimed more at tom.
I reckon that fx4 will rattle the glass,if he removes some of the filter media.


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## Tom Raffield (2 Sep 2018)

This is all very interesting.

I’ll give the empty filter a go and see whether that increases the pressure - I am sure that it will. Then I could reduce some of my media as I do have a tonne in there. That combined with less holes should hopefully see me reach the pressure I need to really kickstart decent (or more adequate) flow around the tank. As trial and error seems like the way to go I may now opt for 25 4mm holes rather than 40. I’ll test my current bar again using tape to see the impact before drilling a new one.


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## Tom Raffield (3 Sep 2018)

So, today's update.

I got home from work and decided to empty the FX4 of all its media (which I have pictured - I did have a lot!). Strangely, as the video shows, the flow did not appear to change at all. What do you think? It looks the same as it did in the video from a few days ago before I started blocking up holes! This did come as a bit of a shock as I was really hoping to see a sudden surge in pressure.



Anyhow, I have decided to reduce the media in the FX4 (see second picture) as I do not believe I need the amount I had. I have also attached a few more photos of some of my plants which are showing negative signs. Must get the flow up! 

Time to go to Plan B which is to make a new spray bar. Who would like to hazard a suggestion as to how many holes and how large to really get some pressure out of the bar; all while hopefully not putting excess stresses back on the pump


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## Andrew Butler (3 Sep 2018)

Tom Raffield said:


> So, today's update.
> 
> I got home from work and decided to empty the FX4 of all its media (which I have pictured - I did have a lot!). Strangely, as the video shows, the flow did not appear to change at all. What do you think? It looks the same as it did in the video from a few days ago before I started blocking up holes! This did come as a bit of a shock as I was really hoping to see a sudden surge in pressure.
> 
> ...




Why not try blocking the holes up with tape again first?


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## Zeus. (3 Sep 2018)

Andrew Butler said:


> Why not try blocking the holes up with tape again first?



Like in the vid with 17 holes the last over the page


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## Matt @ ScapeEasy (3 Sep 2018)

Surprised taking media out did not produce more flow...!


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## Tom Raffield (3 Sep 2018)

I was surprised too. Logically you would expect some kind of increase in pressure, but hey ho.

I’m thinking something along the lines of 20 holes would be required but perhaps at 5ml rather than 4ml. I don’t want to overdo the risk to the pump but equally if none of the previous videos demonstrated enough pressure then I don’t have many options.


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## Matt @ ScapeEasy (3 Sep 2018)

To be on the safe side I would not remove more than 1/3 of your biological media at once...


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## Andrew Butler (4 Sep 2018)

Tom Raffield said:


> the excellent guidance of Andrew


In how not to do it! 



Matt @ ScapeEasy said:


> To be on the safe side I would not remove more than 1/3 of your biological media at once...


I think this was just an experiment to see what difference it made.

Let's look at filter 'Pump output' and 'Filter circulation' as Fluval call it.



 
You can see the massive difference in pump output compared to filter circulation or actual flow rate as I think most of us know it.



john dory said:


> My filter is a fluval 406(1450lph)with the baskets half full of noodles.


Did you know this was the case John?

All information taken from the links below:
http://www.fluvalaquatics.com/media/pdf/fluval-freshwater-brochure.pdf
http://www.fluval-g.com/filterspecs_e.php
http://www.fluvalaquatics.com/us/freshwater/aquarium-filtration/series/fx-series/

As I said before I had a spraybar with my Fluval G6 but the length and design didn't suit me; when I did give it a trial it restricted flow with the slightest bit of build up which leads me to believe they must of calculated holes to give just enough total area.
The supplied spraybar has 14 x 3mm holes giving a total area of 98.96 *BUT* as I say this is either just enough or not quite enough.
When I drill out my new spraybar I'm going to aim for just a little bit more total are than the supplied one. (after testing by blocking up my existing one with tape)
I'm lucky as I can see if my filter flow on the screen so if it is being restricted I know, you don't have this luxury.



Tom Raffield said:


> I’m thinking something along the lines of 20 holes would be required but perhaps at 5ml rather than 4ml


So at the moment you have 48 x 4mm holes which gives you a total area of 603.36
If you were to make it 20 x 4mm holes that would give you a total area of 251.4 and
If you were to make it 20 x 5mm holes that would give you a total area of 392.6
Looking at the comparison between the FX4 and G6 the difference in pump output isn't all that different but the filter circulation is very much so.
If you are to block off holes in you spraybar so you have 25 x 4mm left open and see how that is I don't think you will have any problem and if it isn't enough reduce it down to 20 x 4mm and see how that is.
I think I would be comfortable doing that if it was my filter looking at what I know about the G6, it's supplied spraybar and how it performs.
I'd be tempted to try it first without any media in the filter then see how it is when you add it.

Maybe you could ask Fluval quite how smart the 'Smart pump technology' is in the FX filter.
I do know they don't like you running anything inline or using anything but the supplied fittings or ones designed and sold by them.

I wonder what other peoples' thoughts are?

Keep us updated
Andrew


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## ian_m (4 Sep 2018)

Something like this, is what you are trying to achieve. This a JBLe1501 (1400l/hr) filter with slightly extended spray bar to cover the whole of the back of the tank.



This creates circular flow across the top, down the front and across all the plants. I added a power head as I found there where certain areas in the tank where my drop checker remained blue when CO2 was on.


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## john dory (4 Sep 2018)

Hi Andrew
I wasn't aware of the figures,but I did know the circulation rate was a fair chunk lower than filter output.
Like Ian.. I also use a powerhead which I place over plants that are particularly susceptible to collecting debris.
Actually it's a wavemaker set on about 1250lph constant.


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## Zeus. (4 Sep 2018)

Andrew Butler said:


> I wonder what other peoples' thoughts are?



Comparing surface area of one outlet to the total number of smaller outputs doesn't work as Flow in pipes and the relative resistance is dependant on the diameter of the pipe and its length

So one pipe of 10 surface area will allow more water though the pipe hole than four pipes with 2.5 surface area and it makes a big difference even when all are the same length.

Plus we are using turbulent flow which complicates it even more.

I'm sure Ians spraybar yields much less than the 1400l/hr stated for his filter, But the water is leaving with a higher Velocity so therefore has more energy which increases the tank turnover.


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## Tom Raffield (4 Sep 2018)

So the question is:

Should I stick with the 25mm diameter spray bar pipe and go for 20 or so 4ml holes to increase pressure (how many holes does your bar have @ian_m ?)
or
Should I use a smaller diameter spray bar pipe with more than 20 holes to increase pressure. I have a few pieces that I ordered in error before starting out.

I accept that my filter will not be able to yield as much as is stipulated on the box but I think I must sacrifice this in order to increase the velocity of the water leaving the spray bar. I am sure that my nutrients, CO2 and lighting is all fine and the issues must have come from the flow. Primarily through the Juwel internal filter, then through the poor nozzles on the FX4 and currently through an underpowered spray bar - none have delivered decent flow and distribution.


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## ian_m (4 Sep 2018)

Tom Raffield said:


> (how many holes does your bar have @ian_m ?)


From the video I make it 2 x 9 (whole spray bar) + 6 (shortened spray bar) = 25 holes. This is a standard JBL 22mm spray bar.


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## Zeus. (4 Sep 2018)

Smaller holes can always be made larger  start at 3.0mm and work up in 0.5mm increments


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## Andrew Butler (4 Sep 2018)

Zeus. said:


> Comparing surface area of one outlet to the total number of smaller outputs doesn't work as Flow in pipes and the relative resistance is dependant on the diameter of the pipe and its length





Zeus. said:


> Hi M8
> 
> I use http://www.1728.org/flowrate.htm to get my flow rates when going from a 25mm pipe to many small holes in a spray bar. Using the cross sectional area of the 25mm and comparing to total cross sectional area of the holes in the spray bar doesnt work due to the 'Hagen–Poiseuille law'
> 
> ...


I'm a little confused Karl; you said earlier you calculated your holes the above way and now I think you're saying it doesn't work?


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## Zeus. (4 Sep 2018)

Andrew Butler said:


> I'm a little confused Karl; you said earlier you calculated your holes the above way and now I think you're saying it doesn't work?



I used the calculation to work out the number of holes and size to get the same flow/output which is what you asked for



Andrew Butler said:


> I'm looking to see what size pipe is needed for a filter to operate without being restricted so in other words how big the diameter of a pipe needs to be to allow a particular amount of litres per hour.



But I have posted and getting the energy/output to get the better tank turnover also


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## Zeus. (4 Sep 2018)

I may have been focusing on the Poiseuille’s law too much-  stating 'doubling the radius of a tube decreases resistance by a factor of 
	

	
	
		
		



		
			





' so the size of the pipe makes a big difference to the resistance, but then when have to consider the viscosity of water! 

Water doesnt have a high viscosity, well not as low as a gas

So the 'total area : pipe area rule being the way to go' -may be a close enough approximation for water in our tanks/pipes and filters. As when Andrew used it his results  worked out in the same order as when I used my method which was more long winded also. 

But all said the calculations only give the output in say litres per hour and the guide is x10 tank volume to filter output, but its implementation of the output thats makes the difference to tank turnover/Flow. I had one massive outlet great output and the tank flow was very poor. I fitted the spraybar many small holes which reduced the filters output but the many small 'jets' with high velocity water ' more energy' moved more water within the tank so better turnover/flow


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## Tom Raffield (8 Sep 2018)

Mid way through my tank maintenance for the week. Water is out, plants have been tidied up, snipped and replanted some of the hygrophilia polysperma.

Also taped up half the holes on the spray bar to give me 24 (4mm) holes. FX4 has the same amount of media inside that I reduced to last week. The video shows the results. Much more pressure - might drill a new bar with this number of holes or do you think I should go for more pressure? I did toy with going to a 20mm diameter spray bar from my current 25mm but thought that might be a bridge too far for the pump!


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## Zeus. (8 Sep 2018)

Tom Raffield said:


> I did toy with going to a 20mm diameter spray bar from my current 25mm but thought that might be a bridge too far for the pump



If the 20mm pipe was being feed at both ends maybe, but a 25mm will tend to give similar 'powered' jets of water for the whole length of the pipe but the 20mm will/maybe have more 'powerful' jets at the end where the pipe attaches to the outlet of the filter IMO.

Leave the tape on for a while, mine has had tape over holes for months without it coming off  will take at months to see the results at least, then you may need to tune it further like tape all the holes up and have a different configuration of say 36 (3mm) holes or 24 (3.5mm) holes


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## Tom Raffield (8 Sep 2018)

As I have spare sections of 1m pipe I drilled a new one  There is a little dripping at the left hand side where the filter outlet joins but I have literally bent the FX4 tube, added a Fluval rubber joiner and shoved it into the spray bar. Very technical  If I wasn't worried about cocking it up I would get a proper 90 elbow joint to fit the Fluval+Spray bar and that would allow me to get the spray bar nearer the left tank wall. This is the main area in the tank where I imagine that water movement is lowest.  

For now, I think I'm going to leave everything and just watch and wait. Normal water changes and maintenance and that will be it. I will post results to keep people up to date but possibly not in this spray bar thread. 

_Note: The next thing for playing with (eventually) will be the CO2 diffusion. The nilocg reactor from the states is a no go as it costs almost $80 postage alone! I'd rather pay someone over here to make me one! _


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## foxfish (8 Sep 2018)

Best to use bends rather than elbows, the route from your filter outlet to the spray bar needs to be as direct and smooth as possibly if you want max flow and pressure.


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## Zeus. (9 Sep 2018)

Had a measure and count of my holes today from my spray spraybar which my Fluval FX6 filter feeds post reactors and heaters 4.0mm x23 and 3.5mm x4 the last four just spray on the sides of glass as was getting some surface backflow




no chance of it hitting the glass 1.5m away





Spray bar is 25mm feeds both ends but had to reduce the fitting to 20mm and back to 25mm to fit though the bracing


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## Tom Raffield (14 Sep 2018)

Heading towards tank maintenance tomorrow. 

Spray bar seems to be doing ok. Although when my Fluval stopped, as it is supposed to every 12 hours, there was some serious burping and a surge of bubbles when it turned back on. Could that be my CO2 getting stuck what with the bazooka being aimed straight into it? 

And thought i’d take these photos. Any thoughts on what is still causing it? The black spotting appears to be worse and the orange spotting on the leaves too. I’ve also noticed some GSA on the glass so am putting back the phosphates into my EI mix. My water changes should ensure I never get too much of anything in there. 

Say I haven maxmised my spray bar to its full potential, what other options are there for increasing flow? And just a thought - but will the position of my drift wood totally screw up flow and distribution to the sword on the back left?


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## Matt @ ScapeEasy (15 Sep 2018)

Why do you switch your filter off every 12 hours? Or have I misunderstood?


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## Tom Raffield (15 Sep 2018)

Matt @ ScapeEasy said:


> Why do you switch your filter off every 12 hours? Or have I misunderstood?



It does this automatcially to allow for release of air bubble build up. It’s a feature of the FX series. I probably wasn’t very clear!


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## Zeus. (15 Sep 2018)

Tom Raffield said:


> Although when my Fluval stopped, as it is supposed to every 12 hours, there was some serious burping and a surge of bubbles when it turned back on.



Mine use to do that when I was using it as a CO2 reactor, I compensated for it by having its power switch off say 15 mins before CO2 on time for a minute, then the FX6 could do its auto restart routine then it would be on for 12hrs. But the FX6 couldn't cope with the CO2 I was injecting without throwing bubbles out on its own.

I have the FX6 on a schedule ATM as its output feeds my CO2 reactors so at midnight every day power stops for a minute and the FX6 does its thing and then it doesnt stop mid CO2/Photoperiod, Just another Joy of having a PLC


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## Tom Raffield (1 Oct 2018)

So, a little update.

The tank isn't looking bad. Especially in the middle. The monte carlo however is getting 'dug up' by the shrimp so I may need to rethink the plant i use as foreground there.

Towards the back corners the Amazon swords are growing well but starting to show the orange deficiency on the leaves that I have posted about before. I want to attempt to further increase flow to ensure that CO2 is fully getting around the tank. The corners are partly 'dead spots' due to the spray bar not extending that far and possibly due to the curved front glass of the Vision. 

My thought is: I want to add one of my koralia circulation pumps back into the tank. Do I go in the corner and hope to add circulation there? Although the curved glass might deflect the flow another direction. Or, do I go for the larger koralia and place it slap bang in the middle of the tank under the spray bar. I could drill another spray bar and leave the middle of it blocked. The koralia would act as a central force and I would then get more pressure at the ends of the spray bar. 

I am still on the lookout for a plumbing piece to make the join from my Fluval hose to the bar a little more sound. I am also still investigating options for an inline CO2 diffuser (or similar) with the hope of getting an even better diffusion rate although using the FX4 as a reactor/filter appears to be doing an acceptable job at the moment. 

What do you guys think?


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## Edvet (2 Oct 2018)

Curved tanks are notoriously hard to get good flow in. Experimenting is the key word. Try the cheapest solution first


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## Aquahorti (2 Oct 2018)

If you want good flow, getting a powerhead is probably a better solution than spraybars. The problem with spraybars is the flow entering the turbulent flow regime at the small holes in the spraybar. The problem with turbulent flows is the loss of hydraulic power, and should you want to find out if you are moving towards turbulent flow all you need to do is calculate the Reynolds Number for the fluid flow at the particular point of interest. The hydraulic power is the thing that will make the water do work in the tank, so the more hydraulic power you are losing in the hoses and pipes will result in less flow around the tank.

There are tradeoffs and as Edvet said experimenting is key (unless you have some good fluid dynamics simulation software), but reading a bit about fluid dynamics will give good pointers as to where to go, or just look at what reefers have been doing for years for real shortcuts.


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## Tom Raffield (3 Oct 2018)

Aquahorti said:


> If you want good flow, getting a powerhead is probably a better solution than spraybars. The problem with spraybars is the flow entering the turbulent flow regime at the small holes in the spraybar. The problem with turbulent flows is the loss of hydraulic power, and should you want to find out if you are moving towards turbulent flow all you need to do is calculate the Reynolds Number for the fluid flow at the particular point of interest. The hydraulic power is the thing that will make the water do work in the tank, so the more hydraulic power you are losing in the hoses and pipes will result in less flow around the tank.
> 
> There are tradeoffs and as Edvet said experimenting is key (unless you have some good fluid dynamics simulation software), but reading a bit about fluid dynamics will give good pointers as to where to go, or just look at what reefers have been doing for years for real shortcuts.



I won't pretend to follow all of that! Haha!

I have used multiple circulation pumps in the past which have not worked out. The tank is looking the best it has done for a long, long time and I think this is due to the spray bar and the larger filter (Fluval FX4). The far left hand side is the area where there may be an issue - the plants are telling me this! The largest Koralia I have might be the next thing back into the tank to see if I can help the problem spot but I don't want to have a negative influence somewhere else in the tank.


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## Andrew Butler (3 Oct 2018)

Tom Raffield said:


> The tank is looking the best it has done for a long, long time and I think this is due to the spray bar and the larger filter (Fluval FX4). The far left hand side is the area where there may be an issue - the plants are telling me this!


Hey Tom,
So what you are saying is the spraybar is working right along the tank apart from the section where it doesn't cover?
If this is the case then maybe it's time to revisit ways of getting the feed for the spraybar up and over.............


Tom Raffield said:


> I am still on the lookout for a plumbing piece to make the join from my Fluval hose to the bar a little more sound. I am also still investigating options for an inline CO2 diffuser (or similar) with the hope of getting an even better diffusion rate although using the FX4 as a reactor/filter appears to be doing an acceptable job at the moment.


I know we've talked about it before but you could use a few 90's, maybe even a tee (or 2 if you split it) if your bracing allowed to get the feed up and over - it works fine on my aquarium without causing a drop in flow rate.
This way you could get the spraybar closer to the ends and maybe do away with your dead spot.
As for adding inline CO2 you could tee into your flow; maybe not the best method but it might work.
To do this you could get 2no 25 x 16 x 25mm reducing tees (maybe a couple of 16mm 90s) and put an inline atomiser in a piece of hose along the 16mm - there would be neater ways of doing this.

I think adding any additional powerheads in would significantly disturb the flow pattern you have already.


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