Tops or No Tops?

[Aqua Man]

I agree the temperature does not heat up as much during the period when my metal halides are on; if I remove the tops. I am ok with the excessive evaporation, just want to know your opinion, if the corals get better light with or with out the tops. I would assume the glass would filter out vital energy for the corals, but I have also heard the glass magnifies the light and can cause your corals to grow faster... personaly I do not use tops, just at night when the lights are off to hold in the heat and reduce some evaporation.