look a bit small to me .. both intake and the ventilation that pulls air out .. what is the ventilation size ? 4 inch`s ?
and how big is your room M/3
what kind of temps can you keep .. plants look a bit dropy to me .. but hard to see ..
also .. make the tube and bends as less as possible .. every meter of tubeings and every bends make the ventilation less effective
I would see if I could add the ventilation directly on the filter (make it air tight with some of that Alu tape you got .. and the tube from the vent to out side the room as short and direct as possible ..
I would also move that small fan inside and just make sure I had 2x the size of the ventilation as passive intake
(Etc. a 4 inch vent need atlest 8 inch hole)
don't need a ventilation to pull air in .. its pure physics .. as air is pulld out .. it make a under pressure and pull fresh air/co2 in from every opening .. every !
make sure to keep a little under pressure in the room .. so no smell escapes once they are in flowering and stink ..