Fan & Cooltube Question

G'day

I currently have a 150mm 250cfm centerfugal fan pulling air through 2 150mm cooltubes. The cooltubes pull air directly from my growroom and act as the main exhause.
I am planning on upgrading to 250mm 500cfm can fan or a 200mm 700cfm can fan.

I'm wondering whether I can just reduce the size of 250 or 200mm to 150mm and continue pulling all the air through the cooltube, or whether i'll have to split the flow and pull some directly from the growroom, and some from the cooltube.

Cheers
Grinch

Ok, i went for the 200mm 700cfm can fan, and am just reducing the size. Apparently the only problem will be an increase in sound at the reduction.

Don't suppose anybody can tell me how large to make my passive intakes considering that my outake is 200mm.

Cheers
Grinch

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You kinda have to experiement with the intake size, but I'd say 4" diameter would be a good place to start. You want some suction, just not too much that its dogg'n your fan down.

Thanks Punk