Hello kich87,

It is perfectly fine to run your extractor (exhaust fan in the colonies) continually when your lights are on. This will not dry out the air too much, in fact during flowering the plants should be under 40% relative humidity. Not sure you can even make it too dry for them.

Your temps with the fan on of 25-28C (77-82F) should be OK. With out the fan temps of 29-31C (84-88F) are too high unless you use CO2 supplemention.

BTW; White Rhino is a great strain, very nice indica dom that is one of the strains I've been running for the past few years. One of my favorites.

Hope the info helps you and good luck growing.:thumbsup: