Carbon filter/ballast exhaust recylcing into filter?

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I've got a 400w hps ballast and a 4" carbon filter exhausting out of a 4l x3w x7h cab, and Im putting in another exhaust duct for the stale air remaining up top. Im going to have the scrubber come on for 15 min. every couple hours during dark and full on during the lit 12. I was wondering what, if any, side effects of having the filter/ballast exhaust recylcing back into the filter, so that the added exhaust duct will be the only funky tube coming out. The added exhaust will have an 8-inch inline duct fan pulling the air out 24/7. Besides getting my filter dirty quicker, is there anything wrong with routing it back in? Thanks.

 

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Just saw the typo, 4" ballast connected to a 400 hps, and the 8" duct fan will be pulling the secondary 4" duct, as well as an additional exhaust duct from the veg cab, if that matters. Thx again.

 

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Did I not explain this correctly, or does no one have any type of knowledge concerning the question? Maybe people still think this is high school and there's no time for freshmen. Any response is help, even if its with some cynicism.

 

[Jerry Maine]

I don't quite get you. Try making a diagram, even a rudimentary one. Do you mean having the two exhausts merge into one pipe that blows out the top? Or do you mean the carbon filter / balast exhausts somewhere, and then is blown out via the new exhaust fan along with some stale air? And what is the stale air from, the cab, or somewhere else?

Jerry

 

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Thanks for the response. The filter/ballast exhaust exits the cab, then a second exhaust is pulling out additional air from inside the cab. The second exhuast is not connected to the filter exhaust. I wanted to run the filter exhaust back into filter, thereby creating a loop and having the second exhaust be the only one releasing cabin air out. I just realized that this would just be making the filter less efficient, as it would be just sucking in more of the recycled air as opposed to the ambient air inside the cab... but thanks for the help there, guy.