External carbon filter and fan - suggestions

I have a 3x3x7" tent.
Currently have a can-fan can-light 6" x 27" 600 cfm filter.
Also use can-fan 6" 330 CFM max fan. Combo is tight fit in 36" space.
I am satisfied with both. However, even with the 7’ tent plant height is limited to around 24" because of my light’s hanging distance of 28" above the canopy. In 5 gallon pots and risers, this puts overall plant height at about 36". I dropped the light to about 25" and within a couple of days the top leaves started to cup and tips brown. Raised it to 29’.
In order to obtain additional plant head space I need to move at least the filter and probably the fan outside of the tent.
Somewhere along the way I saw a filter designed or could be modified to to have air exhausted through it (rather than sucked into it as traditionally done). Does anyone know of this filter and can you refer it to me?
Otherwise, if I go with traditional carbon filter is a pre-filter recommended in front of the fan. Pre-filter recommendation. Filter has been used pretty much 24/7 for a year so replacement soon is probably in order. Other options / recommendations appreciated.

Move just the fan out of the tent.
The problem I see with pushing the air through the filter is that they don’t make a pre filter for the interior. This would shorten the life of your expensive filter.
Also, that part of the filter has less surface area. My thought process tells me that would be a less efficient scrubber. Try moving the fan and then putting the filter as high as it can go. Then go from there.

I see all the time companies say that you can push the air through the interior. I reached out to one to see if they made a prefilter for the interior, they were total idiots and condescending. I guess I was the first person to ask this question.

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I’ve got my fan and filter outside the tent with the fan blowing through it and it is working fine.


I think if you push through a charcoal instead of sucking through it…you need to take the filter off the outside and place it in the inside of filter.

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Ok so I run a 135 cfm with 4in ducting probley 10-12 feet to a hole in the foundation of my basement ,had active flow but the noise was alittle much … So I shut that down opened the three velcro vents at the bottom but I also have a swiss cheese veg cabinet in the room also worried about light leaks while still ventalating