I am in the process of setting up a 180g reef tank. The tank is 6' x 2' x 2' give or take an inch. I am using a Trigger Systems Emerald 39 sump. The is no top on the aquarium. I live in Richmond Virginia and keep the house between 70 and 75. About how much evaporation should I expect. I do not have an ATO configured yet. I am adding several gallons a day.