# Spray bar hole size/ number of holes



## Crossocheilus (1 Dec 2014)

My acrylic has finally arrived and I am nearly ready to drill my diy spray bars.

3 sections of JBL spray bar has 27 2mm holes. That makes a combined area of 84.8 mm2.

The internal cross sectional area of the 16/22mm pipe is 201.1mm2.

The reason I am confused is that I have heard people say that the combined area of all holes should = cross sectional area of hose. So what should I do? Having just tested the filter out in the bath with the 3 section spraybar it pushed water out at least a foot horizontally before dropping off.

It's 16/22mm pipe, 1400lph rated JBL filter on a 70cm spray bar for 180L tank.


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## Andy Thurston (1 Dec 2014)

I'd try making the holes in the jbl spray bar bigger 2.5mm to try it. Then if it works drill the same number/size of holes in your acrylic, evenly spaced along the length of acrylic
And i would check your calcs for your existing spraybar
I get 266.479 mm2 for the existing spraybar
And 631.654mm2 for the 16/22 pipe
And 355.30 mm2 for the i/d of the acrylic assuming its 12mm i/d


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## Jose (1 Dec 2014)

Holes area=85 mm2
tube section=201
you want this values to be the same more or less so that you dont lose any energy from the pump in compression of the water. If you have less area in the holes of the pipe the flow will travel faster(the mass of water that goes through the pipe and the holes is the same but the speed isnt unless the the area is the same). normally you want the most flow and this is achieved if you have the minimum resistance between the water and the hose. Less holes mean less surface for the water to travel through and of course more resistance/friction between water and plastic of tube. Ideally you want just a slight preassure so that the water travels to the end of the spraybar, so its better to underestimate the holes by a few.


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## Crossocheilus (1 Dec 2014)

So should I just copy the jbl spray bar? Or is there a better configuration?


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## Jose (1 Dec 2014)

Open as many holes as you need to make both surfaces the same. But try to stay on the lower side because of what I said before.


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