I've had a saltwater tank for a bit over 3 years and today was my first suicide jumper, so I'm not sure yet. For the time being I'll risk fate and continue with the open top. I would like a lid to help cut back on evaporation. With my lights running 8 hours at 15% and holding temp ~78.5F, a full top off chamber last maybe 4-5 days.... Not sure yet how I'm going to work in my ATO for trips when I'm gone for 7+ days.
I found this website that has nice custom tops, but it's a bit pricey and my wallet is still recovering from buying the tank, haha.
http://artfullyacrylic.3dcartstores.com/Red-Sea-MAX-S-Series-650-ClearView-Lid_p_1921.html