Another DIY Spray Bar Headache!

[BigPhil]

Hi all, wondering if you can cure my headache? Sorry this post is a long one!

I've done loads of reading on the correct way to calculate the number and size of the holes required and as such have tried to calculate this correctly and built a series of bars to test this out.

Some details on the build:

Filter: Eheim 2173 Professionel 3 350T (16/22 tubing)
Tank: TMC Signature 900 90cmx45cmx45cm
Powerheads: 2 x Hydor 900 nano

Materials:
I've used 21.5mm overflow pipe for the test and 21.5mm elbow joints to create the angle over the top of the tank wall...

Calculations made:
Cross Sectional Diameter: 201mm2
20 Holes Desired

201 / 20 =10.05
10.05 / 3.14 = 3.2 (Radisu Sq)
Sq Root of 3.2 = 1.78 (Radisu of small)
1.78 * 2 = 3.57
So 20 Holes @ 3mm

Alternate was to build @ 4mm with 15 holes

Testing:

20 holes @ 3mm - only made it across the tank 3/4 of the way
15 holes @ 4mm - Only made it half way across the tank!

Created a new one with 10 holes @ 3mm and this hit the front of the tank with force! SUCCESS!

Well, my question is: The fact that i am using less holes @ 3mm to reach the front of the tank with some force means that i suspect via my calcs that i'm quite under the area of the 16/22 ID which is restricting flow and as such, is this a cause for concern or as i'm hitting the front glass should this be fine?

Any help on this to allow me to get my head around this would be awesome!

Thanks in advance

Phil

 

[Christos Ioannou]

I read that total area of holes on spraybar = 80% area of return hose. This is what I used in my case.

 

[BigPhil]

Hi Christos,

Thanks for the response!

So, my calculations suggest that the total area of the wholes equates to:

3.14 * 2.25 (sq root of hole radius @ 3mm per hole) = 7.065mm2 per hole

7.065 * 10 holes = 70.65

70.65 / 201 = 0.351493 * 100 = 35.15%

Which of course is miles away from even the 80% suggestion...

So, assuming we want to hit the front glass of the tank and my initial calculations were correct, would one assume that the filter is perhaps not up to the job and thus a new filter is a better option than to restrict flow? This is the bit i'm confused with.

I've only just set this tank up a week ago and do have the potential to purchase a new filter (Fluval FX 6 for example) but i'd prefer to not have to spend the money if i can resolve this...

Any suggestions highly welcome!

Thanks

Phil

 

[Christos Ioannou]

My tank is 40 cm wide. Tank is 135x40x35,
The filter is supposed to deliver 2000lph.
The assumption is that the filter has to deliver 10x tank volume to begin with.

 

[Edvet]

Can you put a piece of hose on the filter exit and fill a floating bucket with it, this will give you the volume the filter is putting out when it is "in sito" (after you filled the bucket just dump it in the tank). This will give you an idea wether the filter is up to the job. (maybe eventry to get the water from the spraybar in a bucket (just cover the spraybar with a piece of 32/40 mm pvc and let it run in the bucket)

 

[BigPhil]

My tank is 40 cm wide. Tank is 135x40x35,
The filter is supposed to deliver 2000lph.
The assumption is that the filter has to deliver 10x tank volume to begin with.

Hi Christos,

Yeah agree, in an ideal world the filter would indeed give a 10x turnover in it's own right but at the time i bought this filter it was on a different planted tank and i've ported it across to this. Basically, i read that you don't always need to have the filter working on the 10x rule and you can supplement the turnover with powerheads which is why i have the two Hydor 900 Nanos to compensate...

 

[BigPhil]

Can you put a piece of hose on the filter exit and fill a floating bucket with it, this will give you the volume the filter is putting out when it is "in sito" (after you filled the bucket just dump it in the tank). This will give you an idea wether the filter is up to the job. (maybe eventry to get the water from the spraybar in a bucket (just cover the spraybar with a piece of 32/40 mm pvc and let it run in the bucket)

Hey Edvet,

Yeah that's a good idea... I think I'll try and do that to get an idea of what is happening. My only concern is that the current 'solution' is not getting the relevant turnover due to flow restriction with not enough holes... The Nano's will of course compensate for that but i'm not sure if that's sufficient...

I could be worrying about this WAY too much but i am so keen to get this working and get the tank in it's best possible condition so that the plants thrive which of course can lead to overthinking!

Cheers

Phil