zooh:
DIY the canopy for your lights and fans for ventilation
dont lay acrylic or glass on the tank, it prohibits the gas exchange
aquaboy:
theres nothing wrong with adding 20 gallons a day if thats your evaporation level depending on your climate as long as the water is ro/di and the salinity stays constant.
heres an aatoc for both of ya:
Reef-Relief :: Automated Aquatic Top Off Controller