I am trying to exhaust my veg tent and my flower tent with the same fan. Flower tent is 4 x 8 x 6 and veg tent is 2x4x5.

I have a S&P 6" fan pulling 300 cfm.

Best way to explain this is to work backwards from the exhaust outlet:

6" hard duct (6' run) . . . to

fan . . . to

6" hard duct (2' run) . . . to

6" Y connection

Veg branch from Y connector:

6" to 4" reducer ... to

4" hard duct (4' run) . . . to

Can 33 filter

Flower tent branch from Y connector:

6" Hard duct (8' run) . . . to

Can 33 filter

I am thinking that I need to reduce the short run to the veg filter to a 4" line to even out the vacumn so both filters are pulling the same?

So yeah, that's my question: how can I balance out this split exhaust system?

Thanks in advance.
Buddy

Instead of further restricting the 6" fan by reducing to the 4" duct consider going to a 6" duct to the veg room. Then they should pull evenly. When you use those reducers it restricts the amount of airflow from the smaller duct.

__________________
A bad day in the grow rooms is better than a good day at work!

Hey LT - thanks for the quick response!

So you're thinking that I need to keep both lines at 6" hard duct? Do you think that the pull will be even through both filters even though I have a longer line going to the one filter?

That's the dimension that is creating my question - not sure if the longer run off one side of the Y connector is going to change the balance of pull?

Thanks again. Buddy

That should make no difference at all.

__________________
A bad day in the grow rooms is better than a good day at work!

Thank you - Iwill hook it up that way tomorrow and see how she runs!

Put one in the back and one in the front.

??? Not sure what you are suggesting

I would just use one carbon filter in the flowering room. I'm not sure about your security issues, but the veg room will not really give off any smell unless you are in the actual room messing around with the leaves, and even then its just a faint smell you can smell while you are

LOL! My veg room is dank. I have bonsai moms, seedlings, and clones in there. I love how they smell when they get their water!

The clones cut from flowering plants? Oh yeah, that's some dank too!

Yeah - I need to filter my veg room exhaust.

Buddy

Buddy...

i hate to tell you this, but what you are trying to do is rather difficult... there is no good way to do it... let me explain.

the S&P 6" fan is not REALLY moving 300cfm... it is if you unplug it from the ducts and let it rip, but as soon as you plug it up to a carbon filter... the CFM plummets.

i would consider using that 6" S&P fan ONLY for the veg tent, and getting another one, or a better 6" inline fan for the flower tent... after all it is 4x the size of your veg room.

anyway, if you really must even out the air flow, you will never be able to calculate the effect of changing from 4" duct to 6" on the length of the runs... if you have all 6" you might as well leave it that way... you will have to put some kind of air baffle in the leg off of the Y that is moving fastest... IF you can tell... you really need an airflow meter to be accurate. Also, the internal pressure of the tent will be different... there are more places to pull air into the 4x8 tent than the 2x4 which will make it easier to pull the air through. Air follows the path of least resistance, the carbon is only a piece of the puzzle... duct size is another, and tent pressure is another...

I work with fans and air systems for a living, on a much larger scale... the only way to even them out is the baffle them and oversize the fan slightly.. the headache free way is to get 2 fans

peace