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Reducing pipe size

Tom72

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25 Mar 2021
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Hi folks, recently my oase filtosmart 100 seal failed, and my Heath Robinson repair did not last either, I have not been very impressed with this little filter and has always been problematic. With a waiting list of 6weeks for parts, I am considering buying the bio master 250 Thermo. If I do this can I reduce the 17/22 pipe to 12/16. I ask this so I don’t have to buy new lily pipes.
 

erwin123

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Hi folks, recently my oase filtosmart 100 seal failed, and my Heath Robinson repair did not last either, I have not been very impressed with this little filter and has always been problematic. With a waiting list of 6weeks for parts, I am considering buying the bio master 250 Thermo. If I do this can I reduce the 17/22 pipe to 12/16. I ask this so I don’t have to buy new lily pipes.

I have reduced my 16/22 Fluval 307 to 12/16 hose because my JBJ Chiller is 12/16 and I don't think there is a major effect on flow (you can also compensate by reducing the amount of filter media I guess)
 

ceg4048

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I have reduced my 16/22 Fluval 307 to 12/16 hose because my JBJ Chiller is 12/16 and I don't think there is a major effect on flow (you can also compensate by reducing the amount of filter media I guess)

This is not really true. There is a massive impact of flow throughput when reducing the cross sectional area of piping. The cross sectional area of the 16mm pipe is about 200 sq. mm. That of the 12mm pipe is just over 100 sq. mm. The flow will be proportional to this area, so that is a reduction approaching 50%.

Cheers,
 

erwin123

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ah got it, I am using the 16/22 hose as far as possible and only to reduce to 12/16 only at the point where I need to connect to 12/16 equipment.

In this video George Farmer is using a 12/16 Lily pipe with a 16/22 hose:

 

zozo

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16 Apr 2015
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That's quite a bugger to answer precisely... :)

This one is simple
Φv=vx A

v = Flow Speed m/s
A = ¼πd² = Flow Through Surface Area in m²
Φv = Volume Flow in m³/s

The bugger is "v" and you would need to know the pressure to get the volume in m/s instead of l/h

And that's the one we never get when buying an aquarium pump... Anyway if you can figure out your "v" the above formula can give you a relatively good idea of how much the difference will be between A -12mm or A - 16mm tube.
 
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Zeus.

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The reduction in flow is also related to the length of the reduction in pipe/hose/fitting also, so the shorter the reduction the better. A reduction can also be beneficial as the velocity of the water increases and water entering the tank at a higher velocity increases/creates move flow/tank turnover (if outlets are set up correct).
But any reduction will increase load on the pump also.
At least our pumps are water cooled
 
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