Taking your grow size calculations it's 45 cuft so a 50CFM fan would clear out the grow room once every minute. But other than saying you are using a T5 in a 5x3x5 room - it might be useful to know the number of bulbs and if it's a 4 foot fixture or a 2 foot fixture and the number of bulbs the fixture holds. 4 foot fixtures can come in 1, 2, 4, 6, or 8 bulb set ups. More lights = more heat and need for ventilation.
Isn't it 75 cubic feet l x w x h? And I was assuming if I'm pulling air through a scrubber that a 75 cf fan won't actually be pulling 75 cubic feet? I think it's a 8 lamp system
75 cuft. 4 foot fixture 8 bulbs. Now what's the air temperature generally outside the cabinet? I ask because even in my home the grow closet is upstairs and upstairs is always harder to cool than downstairs. Then again, no one lives upstairs as the children have grown and gone. I keep the ac unit upstairs at 76 degrees and with proper flow through in the closet (exhaust fan 120 cfm for 70 cuft and an oscillating fan inside moving the air inside off the lights) it keeps the temperatures inside right at 78. I also limited my duct work inside the closet to a 90 degree angle duct as the turn limits light leakage and provides a space for my charcoal pantyhose filter system. You don't need much charcoal (about 2 inches works for a small closet) remember HVAC charcoal filters are just an inch thick! I've also bought charcoal ac filters and cut a 4" round piece (bar beer coasters are usually 4" and great templates for cutting through drywall and cutting filters in pieces) put it in the elbow and it works fine. Just change it every 30 days like you would on the wall vent for the house HVAC.
If you have time set up the lights, close the cabinet up and take temperature readings you'll learn more. How long is the needed duct work inside and outside for the flow through along with the scrubber? More distance requires more CFM just as the scrubber does. Do you have any idea how much restriction the scrubber.
