I think your best bet is to create some sort of cover or hood so that you can control the water evaporation in the first place.. then if you need to you can vent that to straight outside using some dryer duct and an exhaust fan. That’ll save a lot of energy over trying to keep the whole basement dry. Putting the exhaust fan on a rheostat so that you can dial the fan speed is even better.. then you can dial it down to right at the point of preventing condensation.. or just keeping a little bit of negative pressure to keep the moisture from leaving the tank.