Acceptable Humidity Levels

[Parker]

What would be an accept table humidity level in the house? I have a total of 460 gallons in the basement with a humidity level hovering around 75 – 80 %. With the recent addition of a 265 my wife noticed the increase humidity in the behavior of her hair ( I laughed at first ) The 265 is no where near ready to run, I have it full for a leak check. The plan was to add an exhaust fan to vent to the outside above the tank. How much could I expect the fan to lower the humidity?