Hi bbc Good air flow throughout your grow room is by far one of the most important aspects of indoor gardening. Plants need a constant supply of fresh air to achieve their maximum growing potential. Proper air exchange also helps to keep the temperature at optimal conditions to prevent any heat related stress on your plants. When choosing a fan remember that its better to have too much air circulation then not enough.
Also remember that if your going to be ducting your exhaust, with numerous bends, or running it through a carbon filter you'll need to increase your CFMs to makeup for those lost due to back pressure.For a grow room 4x6x7 following the recomendatoin that air be changed every 1 to 5 mins the cfm needed to exchange air from a room that size completely every 5 mins would be 33.6 and to remove the air every minute it would be a cfm of 168 so any fan withing these specificatoins would suit you.
carbon filter..Max cfm: 200/350m³/h @ 0.1 sec contact time should be sufficient.6inch one you get then that take 8 inch flanges.
timing depends on the fan and carbon filter you choose.
Yes the odour will get worsat when you get into flower if you are fulling that space then odour control of some sort is highly recomended.hope this was of help to you .i had the converters here cuase im in the prosess of planning a new grow box.be safe the postman.
i appoligise before hand about my spelling and grammar and for the inconsistincy of my posts but when the pain gets bad the morphine comes out and the confusion starts