My flower room is 5'8" x 7'8" and located in my basement. I have a 6" Cloudline and a 4" Cloudline left over from my grow tent days . . . the 6" runs 24/7 @ speed setting 4, the 4" is set to come on if room temps get to 85º, but short of running a heater I run an
HLG Scorpion RSPEC on 12/12 and the 4" fan has never been triggered due to heat . . . basement is climate controlled to 72ºF and 50% RH. I bought the T series fans that came with smart controllers and found out I need to upgrade to the Controller 67 to set minimum fan speeds or connect to their new app.
If I were ordering fans today I would buy the Couldline S6 and add the Controller 67. Don't buy the T series with included smart controller . . . you'll pay like $10 extra for the 67 (and 6" fan), but the minimum speed settings and connected app alone would be worth a lot more than that to me.