Need a 2nd opinion at the number of holes for diy spray bar - The Planted Tank Forum
Old 11-21-2012, 03:06 PM Thread Starter
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Need a 2nd opinion at the number of holes for diy spray bar

Goal: Build a wrap around spray bar for the entire top of my 180 gal tank. There will be 1 foot gap in the back for an over flow box. If my math is correct that is 180 inches of spray bar. Since I will be splitting up the return, it will be 90 inches per spray bar.

Background info: My pump is a Mag Drive 18 which is rate for 1800 gph. After head loss I would say I have about 1200 gph left. From the pump, there will be a T to split the flow into two returns.

According to Hoppy formula for spray holes below is what I came up with. Is this correct?

Forumla: spray bar holes diameter is equal to or less than 0.8 times the pipe inside diameter divided by the square root of the number of spray bar holes.

Spray holes diameter///// Pipe inside diameter///// Number of spray holes///// Holes spacing at 90in - # Holes Per Inch
1/16" 0.06/////////////// 3/4" 0.75//////////////////// 92////////////////////////////// 1.02
3/32" 0.09/////////////// 3/4" 0.75//////////////////// 41////////////////////////////// 0.46
1/8" 0.13/////////////// 3/4" 0.75//////////////////// 23////////////////////////////// 0.26
1/16" 0.06/////////////// 1" 1.00//////////////////// 164////////////////////////////// 0.81
3/32" 0.09/////////////// 1" 1.00//////////////////// 73////////////////////////////// 0.46
1/8" 0.13/////////////// 1" 1.00//////////////////// 41////////////////////////////// 0.46

I'm leaning toward using 3/32" holes with 1" pipe. I will probably won't use the full 73 but more like 60 holes. My question is will this work with my flow being split at the T? Or do I need to reduce it more?

Last, what angle do I aim the spray: straight down, 45 degree, or horizon to the surface? I was thinking alternating between the 45 degree and 22.5 degree to ensure no dead space in the tank.

Last edited by n00dl3; 11-21-2012 at 03:23 PM. Reason: fixing excel table
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Old 11-21-2012, 03:10 PM Thread Starter
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shoot... the excel table is not working... Sorry I don't know how to fix it. Since I'm at work, I can't upload the chart.
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Old 11-21-2012, 04:58 PM
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Aren't Mag pumps more efficient with even larger pipe? I have read on RC to use 1.5" pipe with them as that is what the rating was done with or some such. I know the reason I went to 1" pipe from 3/4" was in the hope of getting another turn over per hour out of my pumps.

Are you sure a wrap around is the best solution? There was a discussion about the ultimate SB a couple months back. The ultimate DIY spray bar, your opinion please

As for the spray bar holes. Do some tests. Pipe is cheap and easy to play with. I would go with Hoppy's suggestion first and use larger rather than smaller holes as lower flow through many holes means they are more likely to clog up. If you don't glue then you can move the pipe around a little to get the angle you like best. Glue up and over the rim of the tank to the point where if the pipe comes off water cannot spray out of the tank. It won't come apart unless you close up the holes so the water pressure is too much for the friction holding the pipe and fittings together.
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Old 11-21-2012, 05:07 PM
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i have 1/8 holes drilled into my shrip tank spraybar.. same flow rate as before, just less force. all plants still sway just fine
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Old 11-21-2012, 05:07 PM
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I would also suggest that you think of actually having some dead space. For the fish!
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Old 11-21-2012, 05:40 PM Thread Starter
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Quote:
Originally Posted by Kathyy View Post
Aren't Mag pumps more efficient with even larger pipe? I have read on RC to use 1.5" pipe with them as that is what the rating was done with or some such. I know the reason I went to 1" pipe from 3/4" was in the hope of getting another turn over per hour out of my pumps.

Are you sure a wrap around is the best solution? There was a discussion about the ultimate SB a couple months back. The ultimate DIY spray bar, your opinion please

As for the spray bar holes. Do some tests. Pipe is cheap and easy to play with. I would go with Hoppy's suggestion first and use larger rather than smaller holes as lower flow through many holes means they are more likely to clog up. If you don't glue then you can move the pipe around a little to get the angle you like best. Glue up and over the rim of the tank to the point where if the pipe comes off water cannot spray out of the tank. It won't come apart unless you close up the holes so the water pressure is too much for the friction holding the pipe and fittings together.
Yes, Mag pump would be more efficient at 1.5". I was trying to create additional head pressure for the spray by downsiding to 1".

Thanks for link... it is very interesting. It does have valid points. I have might have to go back to the drawing board on this one. I will have to do a little more research.
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Old 11-21-2012, 05:43 PM Thread Starter
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Quote:
Originally Posted by HD Blazingwolf View Post
i have 1/8 holes drilled into my shrip tank spraybar.. same flow rate as before, just less force. all plants still sway just fine
I think I need the flow because my tank is 24" deep. I will the force to push the water to the substrate.
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Old 11-21-2012, 05:45 PM Thread Starter
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Quote:
Originally Posted by m00se View Post
I would also suggest that you think of actually having some dead space. For the fish!
Understood but fish are extremely adaptable. They will get use it and I will just have to watch stock in the better.
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Old 11-21-2012, 05:51 PM
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Quote:
Originally Posted by n00dl3 View Post
I think I need the flow because my tank is 24" deep. I will the force to push the water to the substrate.

Force is = to mass x speed

the flow will come out slow but will have more volume per hole..
the force should be roughly the same just keep that in mind.

most fish prefer slower moving water though. they are designed to handle the flow, not always the speed
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Old 11-22-2012, 12:00 AM Thread Starter
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Quote:
Originally Posted by HD Blazingwolf View Post
Force is = to mass x speed

the flow will come out slow but will have more volume per hole..
the force should be roughly the same just keep that in mind.

most fish prefer slower moving water though. they are designed to handle the flow, not always the speed
Understood....

After much more researched, I will be shorten my spray bar to 30" inches each side. Instead of wrapping around the tank. I will be using 1.5" pipe with 1/8" holes. I was thinking having multiple holes with one straight down, one 20 degree, one 45 degree, some at horizontal to the surface of the water for surface agitation.
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