Lighting through a glass top?

[banditpowdercoat]

Would having a glass top, but open sump(in stand w/open back) Limit the O2 transfer and keep heat in? When I upgraded my lights, I had my tank open for a week. Evap was crazy, 1g/day and thats only T5, not MH. I also noticed that the tank temp rose a few deg. Now, with a 5mm glass top, and the TEK 4 tube 24" light tank runs 80.8 in the day, no heater. Evap is less, bout 0.6g/day. I dont want to lose fish due to jumping, nor do I want to be filling RO every day