pipe diameter, flow rate and velocity

[Zeus.]

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

Sounds like a right output killer

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

 

[Zeus.]

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.

 

[foxfish]

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.

 

[john dory]

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.

 

[Andrew Butler]

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?!

 

[Andrew Butler]

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

 

[john dory]

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

 

[Andrew Butler]

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!

 

[john dory]

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.

 

[Tom Raffield]

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.

 

[Tom Raffield]

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

 

[Andrew Butler]

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

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

 

[Zeus.]

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

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

 

[Matt @ ScapeEasy]

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

 

[Tom Raffield]

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.

 

[Matt @ ScapeEasy]

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

 

[Andrew Butler]

the excellent guidance of Andrew

In how not to do it!

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.

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.

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

 

[ian_m]

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.

 

[john dory]

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.

 

[Zeus.]

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.