Ventilation help please

what ever size the intake is on the fan is normally what you would go by

if the intake side is larger then the exhaust then go by what ever the exhaust duct is

the CF is 80 for the numbers u have given us........... are u running a carbon scrubber with it

2 choices here u can run a passive system (simplest just a hole ) u make sure the hole is the farest away from the exhust as possible ....then u add in a clip on 6 inch fan osculating so the air comes in and the fan blows it all in the room and then it is sucked out

2nd choice is to add a intake fan ................this could be a 6 inch booster fan 240cfm with a screen/filter pad it would be lowered to about 80 or 100 ..........u could also get a hempa filter and then rig the fan to suck outside air and the discharge of it goes into the tent/room with the plants all clean air

here is how to figure it out WxLxH then u divide it by 5 ( the room should clear out maximum once every 5 mins ) but it is best to divide it by 3 and that is how strong the fan needs to be

u can go with 6 inch boosters they are 240 cfm and they about 25 bucks with shipping and all from amazon (note speed controllers do not work on booaters)

Thanks for the input. There are two 110 cfm ceiling exhaust fans, that's 220 cfm pulling air up & out of the room. Each bathroom type, exhaust fan has a 4" duct merging into a Y not a T for easy air flow into a scrubber in the atic. What about putting two 6" circular intake holes in, one on each side at the bottom, with changeable filters? Also planned on two wall mounted oscilating fans, one at each end. Sound like a plan or smaller holes, just one? Thanks again,

i would just put 2 4" holes
6" might be overkill

check out a ipower 6" fan and filter combo on ebay