Unless we're missng something by taking the glass lids off you should have a pretty normal evapuration rate. This will mean your salinity will raise unless you top up with RO water. Tunze do a great auto top off system i recommend looking into that one.
Just to add i've never met anyone that keeps the glass lids on their marine aquariums.
Ok thank you. It's the first time I have had a tank this large so was not sure on the glass top.