# Confused on DIY spraybar holes size & spacing



## sowNreap (Jun 10, 2012)

I've read all the threads with the math but guess I'm a math dummy because I still can't grasp it. 

I have 6' long tank with dual corner overflows, wanting to make *two *30" spraybars - one from each corner to go across back of tank. Is it even beneficial to make that long of a spraybar? Would I be better making them shorter?

The pump output is 3/4", return line is 3/4", spraybar will be 3/4"... all regular PVC. 

Can someone please help me figure out hole size & spacing. I can't even figure out where to start.


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## Diana (Jan 14, 2010)

If you want the water action across pretty much the whole tank, then I would drill the holes about 4" apart and test run. If they spray too strongly, then you can drill more holes halfway in between those. 
Start with small holes, too. And if doubling the number of holes still means too strong a spray, then make the holes a tiny bit larger. 

You can run a spray bar with no glue while you are testing, but when you are satisfied it is best to glue it.


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## Aquadawg (Aug 18, 2012)

Diana said:


> If you want the water action across pretty much the whole tank, then I would drill the holes about 4" apart and test run. If they spray too strongly, then you can drill more holes halfway in between those.
> Start with small holes, too. And if doubling the number of holes still means too strong a spray, then make the holes a tiny bit larger.
> 
> You can run a spray bar with no glue while you are testing, but when you are satisfied it is best to glue it.


+1 for Diana


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## sowNreap (Jun 10, 2012)

Yes I would like the action pretty much across the whole tank. When you say start small size what would that be 1/8" or maybe 5/64" would be better. Or is that too small??


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## sowNreap (Jun 10, 2012)

Been trying to work out the math, maybe someone tell me if I did it right. Based this post: http://www.plantedtank.net/forums/showpost.php?p=998384&postcount=7

_To calculate the number of holes in a spray bar to minimize back pressure and maximize flow do the following calculations:

1 Calculate area of outlet on pump. (Pi)(Inside Dia of pump outlet)^2 / 4 _ * Assuming the "^2" means squared so .. 3.14 x 1.5=4.71/4 = 1.1775*

_2 Decide on hole size. I used 1/8" Dia. on mine for a Mag 7 pump._ *would try 5/64" (.0781)*

_3 Calculate area of one hole using above formula_ .. *3.14 x .156=.4898/4 =.1224*

_4 Divide step 1 answer by step 3 answer._* Equals 9.6*

_5 Round down the answer to the next lowest whole number. This is the number of holes you need. The size of the pipe does not matter as long as it is larger or the same as the pump outlet._ *Would be 9*

_6 Space out the holes over the length of your spray bar. If you want them evenly spaced, just do the math and space them out._ *60" /9 = 1 hole every 6.6"* 

*Does that sound right? Don't want to go any smaller hole than 5/64" I don't think, but is having holes spaced that far apart going to do me any good?*


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## Hoppy (Dec 24, 2005)

No, it isn't right. You didn't square the diameters and divide that by 4, then multiply that by pi (3.14). The goal is to have the total area of the spray holes be a little less than the area of the spray bar pipe inside diameter. And, the spray bar pipe inside diameter should be a bit larger than the diameter of the hose connecting to it, or equal to it. When you do that each hole in the spray bar gets about the same flow going through it, spreading the water evenly along the spray bar.

You can first decide how many holes you want in the spray bar. Then make the diameter of each hole be the inside diameter of the spray bar divided by the square root of the number of holes you want. Now, pick a drill size that is slightly smaller than that. So, if the spray bar inside diameter is .75 inches and you want 10 holes, each hole should be .75 divided by the square root of 10, or .75 divided by 3.16, which is .237. The next smaller drill size would be about 7/32 inch.


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## sowNreap (Jun 10, 2012)

Hoppy said:


> No, it isn't right. You didn't square the diameters and divide that by 4, then multiply that by pi (3.14). The goal is to have the total area of the spray holes be a little less than the area of the spray bar pipe inside diameter. And, the spray bar pipe inside diameter should be a bit larger than the diameter of the hose connecting to it, or equal to it. When you do that each hole in the spray bar gets about the same flow going through it, spreading the water evenly along the spray bar.


Guess I'm still confused. Pump outlet inside diameter is .75" .. squared is 1.5", right? Multiplied 1.5 by Pi (3.14) = 4.71, then divided that by 4 = 1.17. 

Am I supposed to use the inside diameter of the 45 degree elbow that connects the 3/4" return pipe to the 3/4" spraybar which would be a bit bigger than the PVC pipe since the 3/4" PVC fits inside it. Other than that it's 3/4" PVC all the way from the pump to the spraybar. 

Other than using 1" PVC for the spraybar I can't really make it bigger. I don't want a spraybar that big. 



Hoppy said:


> You can first decide how many holes you want in the spray bar. Then make the diameter of each hole be the inside diameter of the spray bar divided by the square root of the number of holes you want. Now, pick a drill size that is slightly smaller than that. So, if the spray bar inside diameter is .75 inches and you want 10 holes, each hole should be .75 divided by the square root of 10, or .75 divided by 3.16, which is .237. The next smaller drill size would be about 7/32 inch.


Well that just confused me even more. So are the directions I've been trying to use wrong? 

Using your example of 10 holes of 7/32" would that would be 10 holes across 60" of spraybar? Which would be evenly spaced every 6". So I'm back to where I began but with a much bigger hole size than I mistakenly calculated. Or is it 10 holes for *each *30" spraybar?

Oh nevermind .. I'll figure something out I guess. I give up on math & trying to calculate this out. Having 2 -30" spraybars for a total of 60" makes it even more confusing. Had the tank for 2 months now so what's another week or 2 of trial/error going to hurt. 

I never realized how much trouble this dual corner overflow w/sump tank was going to be. Wish now I hadn't even bought it. Between having to make stand, figure out plumbing & now this spraybar it's just been a PITA and really not worth the effort & time put into it. Sorry just getting very frustrated with the whole thing.

Edit: I do appreciate the help even though I didn't sound like it. Like I said just frustrated. At least it gives me something to work with .. a starting point.


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## Hoppy (Dec 24, 2005)

sowNreap said:


> Guess I'm still confused. Pump outlet inside diameter is .75" .. squared is 1.5", right?


No, .75 squared is .75 X.75=.563


> Multiplied 1.5 by Pi (3.14) = 4.71, then divided that by 4 = 1.17.


.563 multiplied by pi = 1.77. Divide that by 4 = .44


> Am I supposed to use the inside diameter of the 45 degree elbow that connects the 3/4" return pipe to the 3/4" spraybar which would be a bit bigger than the PVC pipe since the 3/4" PVC fits inside it. Other than that it's 3/4" PVC all the way from the pump to the spraybar.


 Use just one number, the .75.


> Other than using 1" PVC for the spraybar I can't really make it bigger. I don't want a spraybar that big.
> 
> 
> Well that just confused me even more. So are the directions I've been trying to use wrong?
> ...


In that example the 10 holes would be for one spray bar, with one inlet. If you make 2 spray bars, each would have 10 holes.


> Which would be evenly spaced every 6". So I'm back to where I began but with a much bigger hole size than I mistakenly calculated. Or is it 10 holes for *each *30" spraybar?
> 
> Oh nevermind .. I'll figure something out I guess. I give up on math & trying to calculate this out. Having 2 -30" spraybars for a total of 60" makes it even more confusing. Had the tank for 2 months now so what's another week or 2 of trial/error going to hurt.
> 
> ...


The shortcut for doing this calculation is to go by diameter, not area. That makes the equation for spraybar holes reduce to: diameter of hole = inside diameter of spraybar divided by the square root of the number of holes you want.


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## sowNreap (Jun 10, 2012)

Thanks Hoppy for explaining that. Obviously I'm just a math idiot. And I must not understand the meaning of "squared".

Oh well, doesn't matter. One bulkhead is leaking. Seems to not want to tighten enough, rocks, leaks from nut or something. Ordering another one which won't be here until Friday .... so I have plenty of time to figure out the spraybar. Just won't be able to test it. 

Definitely been a learning experience. On the bright side gives plenty of time for the paint to cure on the spraybar.

edit: Made progress understanding the math, I think. My math terminology & symbol interpretation were wrong .. I used squared instead of square root. Your shortcut helped a bunch. Thanks.

edit2: well obviously didn't square .75 right, I doubled it instead of multiplying. doh. I now understand squared & square root.


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## Adrand (Feb 13, 2012)

Depending on where it is leaking I have used plumbers putty in the past around the bulkhead to solve leaks. Might be worth a shot.


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## sowNreap (Jun 10, 2012)

Trying again to see if I understand right because it bugs me that I can't (couldn't) figure it out. 

Using the shortcut method (diameter of hole = inside diameter of spraybar divided by the square root of the number of holes you want) for one 30 inch long .75" inside diameter spraybar. *If I want to make 20 holes spaced 1.5 apart .. Square root of 20 = 4.47 so .75 /4.47 = .167 .. which I dropped down to 5/32 drill bit size.* 

Using the other way: 
_1 Calculate area of outlet on pump. (Pi)(Inside Dia of pump outlet)^2 / 4_ - * I get .. 3.14 x .562 = 1.76 /4 = .44 *
_2 Decide on hole size. _- *would use 5/32 (decimal is 0.156)*
_3 Calculate area of one hole using above formula _.. *3.14 x .024 = .075 /4 = .0187*
_4 Divide step 1 answer by step 3 answer._ *.44 / .0187 = 23.5*
_5 Round down the answer to the next lowest whole number. This is the number of holes you need. The size of the pipe does not matter as long as it is larger or the same as the pump outlet._ * 23 holes*
_6 Space out the holes over the length of your spray bar. If you want them evenly spaced, just do the math and space them out. _ *30" /23 = 1.3" so to make things easier would just use 1.5" spacing. *

I would get the same answer if I used 23 holes in the shortcut method so I'm assuming it's correct now. LOL

Just one little mistake the first time caused all this confusion. If I'd only taken .75 *multiplied by* .75 I'd have had this right this first time. Stupid me.


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## sowNreap (Jun 10, 2012)

Adrand said:


> Depending on where it is leaking I have used plumbers putty in the past around the bulkhead to solve leaks. Might be worth a shot.


Yeah I tried that. Didn't help. Tried another bulkhead I had which didn't have a nut so had to use same nut ... but same problem.

When I tighten the nut and then bump the standpipe or drain pipes slightly it causes the bulkhead to move/rock like it's not tight anymore. Like the nut is loosening itself. I can actually tighten it back up. 

One time it seemed to be leaking from under the nut head not above it where it goes up against the glass. Thinking the nut might be bad if that is even possible. I haven't been able to find just a nut for sale so just bought the whole bulkhead.


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## Adrand (Feb 13, 2012)

sowNreap said:


> Yeah I tried that. Didn't help. Tried another bulkhead I had which didn't have a nut so had to use same nut ... but same problem.
> 
> When I tighten the nut and then bump the standpipe or drain pipes slightly it causes the bulkhead to move/rock like it's not tight anymore. Like the nut is loosening itself. I can actually tighten it back up.
> 
> One time it seemed to be leaking from under the nut head not above it where it goes up against the glass. Thinking the nut might be bad if that is even possible. I haven't been able to find just a nut for sale so just bought the whole bulkhead.


Are you hand tightening it or using a tool to crank it? I never rely on only hand tightening alone if so. Ive never heard of a nut going bad but im sure its possible. If there is a defect at all water will find it. Smart move ordering a new one.


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## sowNreap (Jun 10, 2012)

Adrand said:


> Are you hand tightening it or using a tool to crank it? I never rely on only hand tightening alone if so. Ive never heard of a nut going bad but im sure its possible. If there is a defect at all water will find it. Smart move ordering a new one.


I'm only hand tightening as I've read never to use a tool to tighten bulkheads. I do have a tendency to over-tighten when using tools, stripping or breaking them. Maybe previous owner did over-tightened it which kind of stripped it or made a bad spot. 

Aquarium is setup on its stand outside since I have no where to put it until it gets moved into permanent spot in the house. With rain coming I had to stop working on it so I could put tarp back over it. Good thing I stopped when I did, not long after came a huge downpour ... like .25" rain in 15 mins. 

I'm an idiot for not checking the bulkheads sooner. Got side-tracked on making the stand & figuring out plumbing. Should have ordered 1" drain bulkheads at same time I ordered the 3/4" return ones. That's what I get for trying to save a buck .. ended up costing more $ & time in the long run. Live & learn.


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