I evaporate on average 3 gal/day. I have a 120 display and about 40 in the sump/refug. The display has a raised hood w/ 2 175MH and 4 VHO. There are two 3 inch fans in the hood and a 6 inch fan blowing over the sump and a dehumidifier going in the room where sump is that is set at 50%, otherwise all my tools rust!