Now I know you guys in BC dont get alot of cold weather but just some points to ponder
I am in the home building industry and any fan rated higher than 180cfm requires a furnace interlock ... basically if the fan is turned on the furnace kicks in and brings in fresh air from outside to compensate for the air being removed ... the reason is that in winter when all the windows are closed a high powered hoodfan if left on too long can create a vacuum in the house and the only way to get air would be to pull air down the chimney and the burnt gases in the chimney would come back into the house ... carbon monoxide poisoning is next in case you are wondering
The reason I mention this is so that no one makes a fatal mistake in an effort to reduce humidity without taking all necessary steps to protect your families
For over 300 cfm fans a complete air recovery system is required ... this system preheats the outside air so that the house temperature wont drop rapidly because of the amount of air removed/recovered ... obviously more expensive than a interlock
theoretically these systems can be attached to a humidity sensor so that it can all happen automatically
You may surmise that I have given this some thought considering my next tank project will be evaporating some stupid gallons per day
